TNFSF15 facilitates the differentiation of CD11b^(+) myeloid cells into vascular pericytes in tumors

Objective:Immature vasculature lacking pericyte coverage substantially contributes to tumor growth,drug resistance,and cancer cell dissemination.We previously demonstrated that tumor necrosis factor superfamily 15(TNFSF15)is a cytokine with important roles in modulating hematopoiesis and vascular homeostasis.The main purpose of this study was to explore whether TNFSF15 might promote freshly isolated myeloid cells to differentiate into CD11b^(+) cells and further into pericytes.Methods:A model of Lewis lung cancer was established in mice with red fluorescent bone marrow.After TNFSF15 treatment,CD11b^(+) myeloid cells and vascular pericytes in the tumors,and the co-localization of pericytes and vascular endothelial cells,were assessed.Additionally,CD11b^(+) cells were isolated from wild-type mice and treated with TNFSF15 to determine the effects on the differentiation of these cells.Results:We observed elevated percentages of bone marrow-derived CD11b^(+)myeloid cells and vascular pericytes in TNFSF15-treated tumors,and the latter cells co-localized with vascular endothelial cells.TNFSF15 protected against CD11b^(+)cell apoptosis and facilitated the differentiation of these cells into pericytes by down-regulating Wnt3a-VEGFR1 and up-regulating CD49e-FN signaling pathways.Conclusions:TNFSF15 facilitates the production of CD11b^(+) cells in the bone marrow and promotes the differentiation of these cells into pericytes,which may stabilize the tumor neovasculature.

Heterogeneity of tumor-infiltrating myeloid cells in era of single-cell genomics

Tumor microenvironment(TME)is highly heterogeneous and composed of complex cellular components,including multiple kinds of immune cells.Among all immune cells in TME,tumor-infiltrating myeloid cells(TIMs)account for a large proportion and play roles as key regulators in a variety of functions,ranging from immune-mediated tumor killing to tumor immune evasion.Understanding the heterogeneity of TIMs will provide valuable insights for new therapeutic targeting of myeloid cells.Single-cell genomic technologies deciphering cell composition and gene expression at single-cell resolution have largely improved our understanding of the cellular heterogeneity of TIMs and highlighted several novel cell subtypes contributing to the variation of patient survival and treatment response.However,these cell subtypes were defined based on limited data without a concordant nomenclature,which makes it difficult to understand whether they exist in different studies.Thus,in this review,we comprehensively summarized the common agreements and current different opinions on the heterogeneity of TIMs gained from single-cell studies;evaluated the feasibility of current myeloid cell targets at single-cell level and proposed a uniform nomenclature for TIM subsets.

CHARACTERIZING FLUORESCENCE LIFETIME OF NAD(P)H IN HUMAN LEUKEMIC MYELOID CELLS AND MONONUCLEAR CELLS

The aim of this er vito study was to explore the potential of using the fluorescence lifetime of intraellular reduced nicotinamide adenine dinucleotide(phosphate)(NAD(P)H)as a label-free indicator to characterize the di ferencs between human leukemic myeloid cells and normal mononuclear cells(MNC).The steady-state and time-resolved autofuorescence of two human leukemic myeloid cell lines(K562,HL60)and MNC were measured by a spectrofuorimeter.According to excitation-enmission matrix(EEM)analysis,the optimal emission of NAD(P)H in these cells suspensions occurred at 445 nm.Furthermore,the fuorescence lifetimes of NAD(P)H in leukemic myeloid cells and MNC were determined by fitting the time-resolved autofuorescence data.The mean fuorescence lifetimes of NAD(P)H in K562,HL60,and MNC cells were 557±1.19,4.45±0.71,and 7.31±0.60 ns,respectively.There was a significant diference in the mean lifetime of NAD(P)H between leukemic myeloid cells and MNC(p<0.05).The difference was essentally caused by the change in relative concentration of free and protein-bound NAD(P)H.This study suggests that the mean fuorescence lifetime of NAD(P)H might be a potential label-free indicator for differentiating leukemic myeloid cells from MNC.

Expression of triggering receptor-1 in myeloid cells of mice with acute lung injury

BACKGROUND： Myeloid cell （TREM-1） is an important mediator of the signal transduction pathway in inflammatory response. In this study, a mouse model of acute lung injury （ALl） by intraperitoneal injection of lipopolysaccharide （LPS） was established to observe the expression pattern of TREM-1 in lung tissue and the role of TREM-1 in pulmonary inflammatory response to ALl.METHODS： Thirty BALB/C mice were randomly divided into a normal control group （n=6） and an ALl group （n=24）. The model of ALl was made by intraperitonal injection of LPS in dose of 10 mg/ kg. Specimens from peripheral blood and lung tissue were collected 6, 12, 24 and 48 hours after LPS injection. RT-PCR was used to detect TREM-1 mRNA, and ELISA was employed for detection of TREM-1 protein and TNF-a protein, and HE staining was performed for the pathological Smith lung scoring under a light microscope.RESULTS： The expressions of TREM-1 mRNAin lung tissue and blood of the ALl group 6, 12, 24, and 48 hours after injection of LPS were higher than those in the control group. The levels of TREM- 1 protein and the levels of TNF-a protein in lung tissue of the ALl group 6, 12, 24, and 48 hours after LPS injection were higher than those of the control group; the level of TREM-1 protein peaked 12 hours after LPS injection, but it was not significantly correlated with the expression of TREM-1 mRNA （P=0.14）; the TNF-a concentration was positively correlated with TREM-1 levels in lung tissue and with Smith pathological score （r=0.795, P=0.001 ：r=0.499, P=0.034）, but not with the expression of TREM-1 mRNA （P=0.176）.CONCLUSION： The expression of TREM-1 mRNA in lung tissue of mice with ALl is elevated, and the expression of TREM-1 mRNA is related to the level of TNF-a and the severity of inflammatory response to ALl. The expressions of the TREM-1 gene are not consistent with the levels of TREM-1 protein, suggesting a new functional protein involved in immune regulation.

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.

The triggering receptor expressed on myeloid cells 2-apolipoprotein E signaling pathway in diseases

Triggering receptor expressed on myeloid cells 2(TREM2)is a membrane receptor on myeloid cells and plays an important role in the body’s immune defense.Recently,TREM2 has received extensive attention from researchers,and its activity has been found in Alzheimer’s disease,neuroinflammation,and traumatic brain injury.The appearance of TREM2 is usually accompanied by changes in apolipoprotein E(ApoE),and there has been a lot of research into their structure,as well as the interaction mode and signal pathways involved in them.As two molecules with broad and important roles in the human body,understanding their correlation may provide therapeutic targets for certain diseases.In this article,we reviewed several diseases in which TREM2 and ApoE are synergistically involved in the development.We further discussed the positive or negative effects of the TREM2-ApoE pathway on nervous system immunity and inflammation.

Meningeal lymphatic vessel crosstalk with central nervous system immune cells in aging and neurodegenerative diseases

Meningeal lymphatic vessels form a relationship between the nervous system and periphery, which is relevant in both health and disease. Meningeal lymphatic vessels not only play a key role in the drainage of brain metabolites but also contribute to antigen delivery and immune cell activation. The advent of novel genomic technologies has enabled rapid progress in the characterization of myeloid and lymphoid cells and their interactions with meningeal lymphatic vessels within the central nervous system. In this review, we provide an overview of the multifaceted roles of meningeal lymphatic vessels within the context of the central nervous system immune network, highlighting recent discoveries on the immunological niche provided by meningeal lymphatic vessels. Furthermore, we delve into the mechanisms of crosstalk between meningeal lymphatic vessels and immune cells in the central nervous system under both homeostatic conditions and neurodegenerative diseases, discussing how these interactions shape the pathological outcomes. Regulation of meningeal lymphatic vessel function and structure can influence lymphatic drainage, cerebrospinal fluid-borne immune modulators, and immune cell populations in aging and neurodegenerative disorders, thereby playing a key role in shaping meningeal and brain parenchyma immunity.

Comprehensive Understanding of Immune Cells in The Pathogenesis of Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease(NAFLD)is the most common chronic liver disease,defined by several phases,ranging from benign fat accumulation to non-alcoholic steatohepatitis(NASH),which can lead to liver cancer and cirrhosis.Although NAFLD is a disease of disordered metabolism,it also involves several immune cell-mediated inflammatory processes,either promoting and/or suppressing hepatocyte inflammation through the secretion of pro-inflammatory and/or anti-inflammatory factors to influence the NAFLD process.However,the underlying disease mechanism and the role of immune cells in NAFLD are still under investigation,leaving many open-ended questions.In this review,we presented the recent concepts about the interplay of immune cells in the onset and pathogenesis of NAFLD.We also highlighted the specific non-immune cells exhibiting immunological properties of therapeutic significance in NAFLD.We hope that this review will help guide the development of future NAFLD therapeutics.

Conditional Knockout of Src Homology 2 Domain-containing Protein Tyrosine Phosphatase-2 in Myeloid Cells Attenuates Renal Fibrosis after Unilateral Ureter Obstruction

Background：Src homology 2 domain-containing protein tyrosine phosphatase-2 （SHP-2） is a kind of intracellular protein tyrosine phosphatase.Studies have revealed its roles in various disease,however,whether SHP-2 involves in renal fibrosis remains unclear.The aim of this study was to explore the roles of myeloid cells SHP-2 in renal interstitial fibrosis.Methods：Myeloid cells SHP-2 gene was conditionally knocked-out （CKO） in mice using loxP-Cre system,and renal interstitial fibrosis was induced by unilateral ureter obstruction （UUO）.The total collagen deposition in the renal interstitium was assessed using picrosirius red stain.F4/80 immunostaing was used to evaluate macrophage infiltration in renal tubular interstitium.Quantitative real-time polymerase chain reaction and enzyme linked immunosorbent assay were used to analyze the production of cytokines in the kidney.Transferase-mediated dUTP nick-end labeling stain was used to assess the apoptotic renal tubular epithelial cells.Results：Src homology 2 domain-containing protein tyrosine phosphatase-2 gene CKO in myeloid cells significantly reduced collagen deposition in the renal interstitium after UUO.Macrophage infiltration was evidently decreased in renal tubular interstitium of SHP-2 CKO mice.Meanwhile,the production of pro-inflammatory cytokines was significantly suppressed in SHP-2 CKO mice.However,no significant difference was observed in the number of apoptotic renal tubular epithelial cells between wild-type and SHP-2 CKO mice.Conclusions：Our observations suggested that SHP-2 in myeloid cells plays a pivotal role in the pathogenesis of renal fibrosis,and that silencing of SHP-2 gene in myeloid cells may protect renal from inflammatory damage and prevent renal fibrosis after renal injury.

Establishment of induced pluripotent stem cells from aged mice using bone marrow-derived myeloid cells

If induced pluripotent stem(iPS)cells are to be used to treat damaged tissues or repair organs in elderly patients,it will be necessary to establish iPS cells from their tissues.To determine the feasibility of using this technology with elderly patients,we asked if it was indeed possible to establish iPS cells from the bone marrow(BM)of aged mice.BM cells from aged C57BL/6 mice carrying the green fluorescence protein(GFP)gene were cultured with granulocyte macrophage-colony stimulating factor(GM-CSF)for 4 days.Four factors(Oct3/4,Sox2,Klf4 and c-Myc)were introduced into the BM-derived myeloid(BM-M)cells.The efficiency of generating iPS cells from aged BM cultured in GM-CSF was low.However,we succeeded in obtaining BM-M-iPS cells from aged C57BL/6 mice,which carried GFP.Our BM-M-iPS cells expressed SSEA-1 and Pou5f1 and were positive for alkaline phosphatase staining.The iPS cells did make teratoma with three germ layers following injection into syngeneic C57BL/6 mice,and can be differentiated to three germ layers in vitro.By co-culturing with OP9,the BM-M-iPS cells can be differentiated to the myeloid lineage.The differentiated BM-M-iPS cells proliferated well in the presence of GM-CSF,and lost expression of Nanog and Pou5f1,at least in part,due to methylation of their promoters.On the contrary,Tnf and Il1b gene expression was upregulated and their promoters were hypomethylated.

Pik3c3 deficiency in myeloid cells imparts partial resistance to experimental autoimmune encephalomyelitis associated with reduced IL-1βproduction

The PIK3C3/VPS34 subunit of the class III phosphatidylinositol 3-kinase(PtdIns3K)complex plays a role in both canonical and noncanonical autophagy,key processes that control immune-cell responsiveness to a variety of stimuli.Our previous studies found that PIK3C3 is a critical regulator that controls the development,homeostasis,and function of dendritic and T cells.In this study,we investigated the role of PIK3C3 in myeloid cell biology using myeloid cell-specific Pik3c3-deficient mice.We found that Pik3c3-deficient macrophages express increased surface levels of major histocompatibility complex(MHC)class I and class II molecules.In addition,myeloid cell-specific Pik3c3 ablation in mice caused a partial impairment in the homeostatic maintenance of macrophages expressing the apoptotic cell uptake receptor TIM-4.Pik3c3 deficiency caused phenotypic changes in myeloid cells that were dependent on the early machinery(initiation/nucleation)of the classical autophagy pathway.Consequently,myeloid cell-specific Pik3c3-deficient animals showed significantly reduced severity of experimental autoimmune encephalomyelitis(EAE),a primarily CD4^(^(+))T-cell-mediated mouse model of multiple sclerosis(MS).This disease protection was associated with reduced accumulation of myelin-specific CD4^(^(+))T cells in the central nervous system and decreased myeloid cell IL-1βproduction.Further,administration of SAR405,a selective PIK3C3 inhibitor,delayed disease progression.Collectively,our studies establish PIK3C3 as an important regulator of macrophage functions and myeloid cell-mediated regulation of EAE.Our findings also have important implications for the development of small-molecule inhibitors of PIK3C3 as therapeutic modulators of MS and other autoimmune diseases.

Degradation-resistant implanted biomaterials establish an immunosuppressive microenvironment that induces T cell exhaustion by recruiting myeloid cells

Implanted biomaterials have transformed healthcare and the treatment of injury and disease,but their infuence on the local immune landscape remains unclear.Here we discovered that degradation-resistant titanium-based implants establish an immunosuppressive microenvironment by recruiting myeloid cells,including monocytes,macrophages,neutrophils,and myeloid-lineage dendritic cells.Unlike normal tissues,the tissues nearby implants exhibit an chronic inflamed and immunosuppressive status characterised by myeloid-rich,T cell-exhaustion gene signature by single-cell RNA sequencing.Vitamin C treatment provides an effective strategy to rescue the immunosuppressive microenvironment,which can be used as a regular supplement to reduce the risk of malignant cell survival around the implants.

Role of myeloid cells in the tumor microenvironment

The dynamic interplay between tumor cells and immune cells in the microenvironment plays a crucial role in determining disease severity and therapeutic outcome in cancer.Myeloid cells are the most abundantly available cell population in the tumor microenvironment.Myeloid cells have been shown to exist in diverse phenotypes and play both antitumoral and protumoral roles in cancer.Understanding the biology of myeloid cells can lay the foundation for the development of therapeutic strategies aimed at enhancing the antitumoral role of myeloid cells.This article presents an overview of the role of myeloid cells in tumor development and various mechanisms by which myeloid cells aid tumor progression.Existing drugs against cancer that utilize myeloid cells and the role of myeloid cells in drug resistance are also discussed.

Hepatopoietin Cn suppresses apoptosis of human hepatocellular carcinoma cells by up-regulating myeloid cell leukemia-1

AIM:To investigate the role of hepatopoietin Cn(HPPCn) in apoptosis of hepatocellular carcinoma(HCC)cells and its mechanism. METHODS:Two human HCC cell lines,SMMC7721 and HepG2,were used in this study.Immunostaining, Western blotting and enzyme linked immunosorbent assay were conducted to identify the expression of HPPCn and the existence of an autocrine loop of HPPCn/ HPPCn receptor in SMMC7721 and HepG2.Apoptotic cells were detected using fluorescein isothiocyanate (FITC)-conjugated Annexin V and propidium iodide.RESULTS:The HPPCn was highly expressed in human HCC cells and secreted into culture medium(CM). FITC-labeled recombinant human protein(rhHPPCn) could specifically bind to its receptor on HepaG2 cells. Treatment with 400 ng/mL rhHPPCn dramatically increased the viability of HCC-derived cells from 48.1% and 36.9%to 85.6%and 88.4%,respectively(P< 0.05).HPPCn silenced by small-interfering RNA reduced the expression and secretion of HPPCn and increased the apoptosis induced by trichostatin A.Additionally, HPPCn could up-regulate the expression of myeloid cell leukemia-1(Mcl-1)in HCC cells via mitogen-activated protein kinase(MAPK)and sphingosine kinase-1. CONCLUSION:HPPCn is a novel hepatic growth factor that can be secreted to CM and suppresses apoptosis of HCC cells by up-regulating Mcl-1 expression.

LILRB4, an immune checkpoint on myeloid cells

Leukocyte immunoglobulin-like receptor B4(LILRB4)is an inhibitory receptor in the LILR family mainly expressed on normal and malignant human cells of myeloid origin.By binding to ligands,LILRB4 is activated and subsequently recruits adaptors to cytoplasmic immunoreceptor tyrosine inhibitory motifs to initiate different signaling cascades,thus playing an important role in physiological and pathological conditions,including autoimmune diseases,microbial infections,and cancers.In normal myeloid cells,LILRB4 regulates intrinsic cell activation and differentiation.In disease-associated or malignant myeloid cells,LILRB4 is significantly correlated with disease severity or patient survival and suppresses T cells,thereby participating in the pathogenesis of various diseases.In summary,LILRB4 functions as an immune checkpoint on myeloid cells and may be a promising therapeutic target for various human immune diseases,especially for cancer immunotherapy.

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.

Flow cytometry assay of myeloid dendritic cells (mDCs)in peripheral blood during acute hepatitis C:Possible pathogenetic mechanisms

AIM： To asses the expression of myeloid dendritic cells （CD11c＋） subset during acute HCV hepatitis and its possible involvement in natural history of the infection.METHODS： We enrolled 11 patients with acute hepatitis C （AHC） （Group A）, 10 patients with acute hepatitis A （AHA） （as infective control-Group B） and 10 healthy donors （group C） in this study. All patients underwent selective flow cytometry gating strategies to assess the peripheral number of the myeloid dendritic cells （mDCs） to understand the possible role and differences during acute hepatitis.RESULTS： Eight of 11 patients with acute HCV hepatitis did not show any increase of mDCs compared to healthy individuals, while a significant decrease of mDCs was found in absolute cell count （z=-2.37, P〈0.05） and percentage （z=-2.30; P〈 0.05） as compared with AHA. On the contrary, The remaining three patients of the group A had a higher mDCs number and percentage as occur in group B. Interestingly, after six months, those patients did not show any increase of mDCs subset were chronically infected, while the three subjects with an increase of peripheral mDCs, as in HAV acute infection, resolved the illness.CONCLUSION： The lack of increase of mDCs during acute hepatitis C might be an important factor involved in chronicization of the infection.

Higher PD-1 expression concurrent with exhausted CD8+ T cells in patients with de novo acute myeloid leukemia

Objective： To investigate the association between the T cell inhibitory receptor programmed death 1（PD-1）and T cell exhaustion status in T cells from patients with de novo acute myeloid leukemia（AML） and AML in complete remission（CR）.Methods：Surface expression of PD-1 and the exhaustion and immunosenescence markers CD244 and CD57 on CD3＋,CD4＋ and CD8＋ T cells from peripheral blood samples from 20 newly diagnosed,untreated AML patients and 10 cases with AML in CR was analyzed by flow cytometry.Twenty-three healthy individuals served as control.Results：A significantly higher percentage of PD-1＋ cells were found for CD3＋ T cells in the de novo AML group compared with healthy controls.In addition,an increased level of PD-1＋ CD8＋ T cells,but not PD-1＋ CD4＋,was found for CD3＋ T cells in the de novo AML and AML-CR samples.A higher percentage of CD244＋ CD4＋,CD244＋ CD8＋,CD57＋ CD4＋ and CD57＋ CD8＋ T cells was found in CD3＋ T cells in samples from those with de novo AML compared with those from healthy controls.Strong increased PD-1＋ CD244＋ and PD-1＋ CD57＋ coexpression was found for CD4＋ and CD8＋ T cells in the de novo AML group compared with healthy controls.Conclusions：We characterized the major T cell defects,including co-expression of PD-1 and CD244,CD57-exhausted T cells in patients with de novo AML,and found a particular influence on CD8＋ T cells,suggesting a poor anti-leukemia immune response in these patients.

The role of myeloid cells in prevention and control of group A streptococcal infections

Group A Streptococcus(GAS;Streptococcus pyogenes)is one of the most versatile bacteria among human pathogens.Non-invasive GAS infections can cause common diseases,such as pharyngitis and impetigo.Severe invasive GAS infections can lead to rapid progressive and life-threatening manifestations,including necrotizing fasciitis and streptococcal toxic shock syndrome with high mortality rates ranging from 30%to 70%.Therefore,GAS is also known as"killer microbes"or"flesh-eating bacteria".During severe invasive GAS infections,anti-bacterial immunity is impeded by attenuation of the cellular components of innate immune responses.However,this loss of protection is compensated for by interferon-γ-producing immature myeloid cells,which are recruited upon severe invasive GAS infections in mouse models.In this review,we discuss and summarize the current knowledge on the role of interferon-γ-producing myeloid cells and other myeloid cells in the prevention and control of severe invasive GAS infections.

Effects of methionine enkephalin on immune enhancement by reducing myeloid derived suppressor cells and reprogramming liver metabolism in colon cancer mice

OBJECTIVE To investigate enhanced immune function of methionine encephalin(MENK)and its anti-tumor mechanism in CT26 colon cancer mouse model.METHODS 3×10~6CT26 cells were implanted subcutaneously in BALB/c mice.Four days after,MENK was peritoneally administrated at the concentration of 20 mg·kg^(-1) for 14 d.The percentage of MDSCs in bone marrow,spleen,blood,tumor and liver were detected by flow cytometry.Non-esterified fatty acid(NEFA),triglycerides(TG)and total cholesterol(T-CHO)in liver homogenate were tested by a NEFA test kit,a TG test kit and a T-CHO test kit respectively.qRT-PCR and Western blot were used to measure m RNA and protein levels of inflammation-,glycometabolsim-and lipometabolsim-associated indexes in liver.RESULTS MENK decreased percentages of MDSCs in bone marrow,spleen,blood and tumor in colon cancer mice.MENK-treated mice displayed elevated ratio of CD4^+T and CD8^+T cells in spleen as well as increased T and B lymphocytes proliferation.Meanwhile,MENK also ameliorated liver damage reflected by lower levels of GPT and GOT in serum and reduced risks of cancer-associated index including inflammation,high lipid and high glucose.Furthermore,MENK lowered down the levels of NEFA,TG and T-CHO in liver homogenate.MENK treatment decreased expression of p-STAT3,increased expression of p-AKT,IRS1 and Glut4 at protein level as well as reduced lipogenesis-associated genes and elevated glycolysis-associated genes in liver of tumor bearing mice.Also,abated expression of genes associated with MDSCs generation(M-CSF,GM-CSF,IL-6,IL^(-1)β)and migration(S100A9,KC)was observed within shrunken subcutaneous tumor by MENK intervention.CONCLUSION MENK has the ability to strength immune function against colon cancer by reducing MDSCs and improving liver metabolism.