The protective role of myeloid-derived suppressor cells in concanavalin A-induced hepatic injury

The mechanism underlying T cell-mediated fulminant hepatitis is not fully understood. In this study, we investigated whether myeloid derived suppressor cells (MDSCs) could prevent the concanavalin A (ConA)- induced hepatitis through suppressing T cell proliferation. We observed an increase in the frequencies of MDSCs in mouse spleen and liver at early stage of ConA treatment, implicating that the MDSCs might be involved in the initial resistance of mice against ConAmediated inflammation. Subpopulation analysis showed that the MDSCs in liver of ConA-induced mice were mainly granulocytic MDSCs. Adoptive transfer of the bone marrow-derived MDSCs into ConA-treated mice showed that the MDSCs migrated into the liver and spleen where they suppressed T cell proliferation through ROS pathway. In addition, the frequencies of MDSCs in mice were also significantly increased by the treatment with immune suppressor glucocorticoids. Transfer of MDSCs into the regulatory T cell (Treg)- depleted mice showed that the protective effect of MDSCs on ConA-induced hepatitis is Treg-independent. In conclusion, our results demonstrate that MDSCs possess a direct protective role in T cell-mediated hepatitis, and increasing the frequency of MDSCs by either adoptive transfer or glucocorticoid treatment represents a potential cell-based therapeutic strategy for the acute inflammatory disease.     

Stem cells from human exfoliated deciduous teeth ameliorate concanavalin A-induced autoimmune hepatitis by protecting hepatocytes from apoptosis

BACKGROUNDAutoimmune hepatitis is a serious autoimmune liver disease that threatens human health worldwide, which emphasizes the urgent need to identify novel treatments. Stem cells from human exfoliated deciduous teeth (SHED), which are easy to obtain in a non-invasive manner, show pronounced proliferative and immunomodulatory capacities.AIMTo investigate the protective effects of SHED on concanavalin A (ConA)-induced hepatitis in mice, and to elucidate the associated regulatory mechanisms.METHODSWe used a ConA-induced acute hepatitis mouse model and an in vitro co-culture system to study the protective effects of SHED on ConA-induced autoimmune hepatitis, as well as the associated underlying mechanisms.RESULTSSHED infusion could prevent aberrant histopathological liver architecture caused by ConA-induced infiltration of CD3⁺, CD4⁺, tumor necrosis-alpha⁺, and interferon-gamma⁺ inflammatory cells. Alanine aminotransferase and aspartate aminotransferase were significantly elevated in hepatitis mice. SHED infusion could therefore block ConA-induced alanine aminotransferase and aspartate aminotransferase elevations. Mechanistically, ConA upregulated tumor necrosis-alpha and interferon-gamma expression, which was activated by the nuclear factor-kappa B pathway to induce hepatocyte apoptosis, resulting in acute liver injury. SHED administration protected hepatocytes from ConA-induced apoptosis. CONCLUSIONSHED alleviates ConA-induced acute liver injury via inhibition of hepatocyte apoptosis mediated by the nuclear factor-kappa B pathway. Our findings could provide a potential treatment strategy for hepatitis.     

Inhibition of neuronal necroptosis mediated by RIP1/RIP3/MLKL provides neuroprotective effects on kaolin‐induced hydrocephalus in mice

ObjectivesNecroptosis is widespread in neurodegenerative diseases. Here, we examined necroptosis in the hippocampus and cortex after hydrocephalus and found that a necroptosis pathway inhibitor alleviates necroptosis and provides neuroprotective effects.Materials and methodsHydrocephalus was induced in C57BL/6 mice by kaolin. Haematoxylin and eosin (HE), Nissl, PI and Fluoro‐Jade B (FJB) staining were used for general observations. Phosphorylated receptor‐interacting protein kinase 3 (p‐RIP3) and phosphorylated mixed lineage kinase domain‐like (p‐MLKL) were measured by Western blotting and immunohistochemistry. Scanning electron microscopy (SEM) was used to observe ependymal cilia. Magnetic resonance imaging (MRI) and the Morris water maze (MWM) test were used to assess neurobehavioral changes. Immunofluorescence was used to detect microglial and astrocyte activation. Inflammatory cytokines were measured by Western blotting and RT‐PCR.ResultsObvious pathological changes appeared in the hippocampus and cortex after hydrocephalus, and expression of the necroptosis markers p‐RIP3, p‐MLKL and inflammatory cytokines increased. Necrostatin‐1 (Nec‐1) and GSK872 reduced necrotic cell death, attenuated p‐RIP3 and p‐MLKL levels, slightly improved neurobehaviours and inhibited microglial and astrocyte activation and inflammation.ConclusionsRIP1/RIP3/MLKL mediates necroptosis in the cortex and hippocampus in a hydrocephalus mouse model, and Nec‐1 and GSK872 have some neuroprotective effects.     

Circulating myeloid-derived suppressor cells: An independent prognostic factor in patients with breast cancer

Evading immune destruction is a hallmark of cancer. Myeloid-derived suppressor cells (MDSCs), a heterogeneous population of myeloid immune cells, are thought to foster the establishment of an immunosuppressive tumor microenvironment, but it remains unclear how. This study aims to determine the levels of circulating MDSCs and their subpopulations and test their immunosuppressive functions in patients with breast cancer (BC). We analyzed the fractions of MDSCs in freshly isolated peripheral blood mononuclear cells of patients with BC and healthy donors using flow cytometry. Circulating MDSCs were further phenotyped using fluorescently labeled antihuman monoclonal antibodies. Coculture experiments revealed the effects of MDSCs on CD3⁺ T cell response. Moreover, we correlated circulating MDSC levels with clinicopathological features of patients with BC. We show that the fraction of HLA-DR ^– CD33 ⁺ MDSCs in peripheral blood is about 10-fold higher in patients with BC than in healthy control individuals. The levels of all MDSC subpopulations, including monocytic and granulocytic MDSCs, are significantly elevated. Coculture experiments of purified HLA-DR ^– CD33 ⁺ MDSCs and CD3 ⁺ T cells demonstrate that T cell proliferation is more effectively inhibited by BC patient-derived MDSCs than by healthy control MDSCs. Moreover, increased circulating MDSC levels robustly associate with advanced BC stage and positive lymph node status. By being more abundant and more effective T cell suppressors, BC patient-derived circulating MDSCs exert a dual immunosuppressive effect. Our findings pave the way to develop novel diagnostic and immunotherapeutic strategies, aimed at detecting and inhibiting MDSCs in patients with BC.     

The Calcineurin-NFAT Axis Controls Allograft Immunity in Myeloid-Derived Suppressor Cells through Reprogramming T Cell Differentiation

While cyclosporine (CsA) inhibits calcineurin and is highly effective in prolonging rejection for transplantation patients, the immunological mechanisms remain unknown. Herein, the role of calcineurin signaling was investigated in a mouse allogeneic skin transplantation model. The calcineurin inhibitor CsA significantly ameliorated allograft rejection. In CsA-treated allograft recipient mice, CD11b⁺ Gr1⁺ myeloid-derived suppressor cells (MDSCs) were functional suppressive immune modulators that resulted in fewer gamma interferon (IFN-γ)-producing CD8⁺ T cells and CD4⁺ T cells (T_H1 T helper cells) and more interleukin 4 (IL-4)-producing CD4⁺ T cells (T_H2) and prolonged allogeneic skin graft survival. Importantly, the expression of NFATc1 is significantly diminished in the CsA-induced MDSCs. Blocking NFAT (nuclear factor of activated T cells) with VIVIT phenocopied the CsA effects in MDSCs and increased the suppressive activities and recruitment of CD11b⁺ Gr1⁺ MDSCs in allograft recipient mice. Mechanistically, CsA treatment enhanced the expression of indoleamine 2,3-dioxygenase (IDO) and the suppressive activities of MDSCs in allograft recipients. Inhibition of IDO nearly completely recovered the increased MDSC suppressive activities and the effects on T cell differentiation. The results of this study indicate that MDSCs are an essential component in controlling allograft survival following CsA or VIVIT treatment, validating the calcineurin-NFAT-IDO signaling axis as a potential therapeutic target in transplantation.     

Development of a Spontaneous Liver Disease Resembling Autoimmune Hepatitis in Mice Lacking Tyro3, Axl and Mer Receptor Tyrosine Kinases

Autoimmune hepatitis (AIH) is a severe type of chronic liver disease. The lack of appropriate animal models has resulted in a limited understanding regarding the etiology of AIH. Here, we demonstrated that mice deficient in Tyro3, Axl and Mer (TAM) receptor tyrosine kinases (RTKs) developed persistent inflammatory liver damage resembling AIH. Tyro3^−/−Axl^−/−Mer^−/− triple mutant (TAM^−/−) mice exhibited chronic hepatitis, manifested by progressive appearance of interface hepatitis, immune cell infiltrations and elevated inflammatory cytokine levels in the liver. Accordingly, increased levels of transaminases were observed. Moreover, characteristic autoantibodies and high levels of plasma immunoglobulin G for AIH were detected as TAM^−/− mice aged. Finally, we provided evidence that the liver damage in TAM^−/− mice mainly result from bone marrow-derived cells and could be rescued by transplantation of WT bone marrow cells. Results suggest that TAM RTKs play an important role in maintaining immune tolerance of the liver.     

CD8+ T cells exhaustion induced by myeloid‐derived suppressor cells in myelodysplastic syndromes patients might be through TIM3/Gal‐9 pathway

CD8⁺ T cells play a central role in antitumour immunity, which often exhibit ‘exhaustion’ in the setting of malignancy and chronic viral infection due to T cell immunoglobulin and mucin domain 3 (TIM3) and myeloid‐derived suppressor cells (MDSCs). Our team previously found that overactive MDSCs and exhausted TIM3⁺CD8⁺ T cells were observed in myelodysplastic syndromes (MDS) patients. However, it is not obvious whether MDSCs suppress CD8⁺ T cells through TIM3/Gal‐9 pathway. Here, Gal‐9, as the ligand of TIM3, was overexpressed in MDSCs. The levels of Gal‐9 in bone marrow supernatants, serum and culture supernatants of MDSCs from MDS patients were elevated. CD8⁺ T cells from MDS or normal controls produced less perforin and granzyme B and exhibited increased early apoptosis after co‐culture with MDSCs from MDS. Meanwhile, the cytokines produced by CD8⁺ T cells could be partially restored by TIM3/Gal‐9 pathway inhibitors. Furthermore, CD8⁺ T cells produced less perforin and granzyme B after co‐culture with excess exogenous Gal‐9, and the function of CD8⁺ T cells was similarly restored by TIM3/Gal‐9 pathway inhibitors. Expression of Notch1, EOMES (associated with perforin and granzyme B secretion), p‐mTOR and p‐AKT (associated with cell proliferation) was decreased in CD8⁺ T cells from MDS after co‐culture with excess exogenous Gal‐9. These suggested that MDSCs might be the donor of Gal‐9, and TIM3/Gal‐9 pathway might be involved in CD8⁺ T cells exhaustion in MDS, and that TIM3/Gal‐9 pathway inhibitor might be the promising candidate for target therapy of MDS in the future.     

CD1d is a novel cell-surface marker for human monocytic myeloid-derived suppressor cells with T cell suppression activity in peripheral blood after allogeneic hematopoietic stem cell transplantation

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of cells that regulate immune responses in cancer and various pathological conditions. However, the phenotypic and functional heterogeneity of human MDSCs represents a major hurdle for the development of therapeutic strategies targeting or regulating MDSCs in tumor progression, inflammation, and graft-versus-host disease (GVHD). We previously shown that circulating HLA-DR^-CD14⁺ monocytic MDSCs are a major contributor to clinical outcomes after allogeneic hematopoietic stem cell transplantation (allo-HSCT). In this study, we identified, using high-throughput screening, a set of surface markers that are strongly expressed in HLA-DR^-CD14⁺ monocytic MDSCs isolated from the peripheral blood (PB) of patients receiving allo-HSCT. Subsequent experiments showed the consistent dominant expression of CD1d in monocytic MDSCs of allo-HSCT PB in comparison with granulocytic MDSCs. In addition, CD1d-expressing cells isolated from PB of allo-HSCT patients showed the suppressive activity of T cell proliferation and higher expression of MyD88 and IDO compared with CD1d^? cells. Our results suggest that CD1d could be a valuable marker for further therapeutic evaluation of human monocytic MDSCs for immune-related diseases, including GVHD.     

Myeloid-derived suppressor cells regulate the immunosuppressive functions of PD-1−PD-L1+ Bregs through PD-L1/PI3K/AKT/NF-κB axis in breast cancer

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of myeloid cells that are closely related to tumor immune escape, but the mechanism by which MDSCs regulate B cells has not been elucidated. Our previous studies revealed that breast cancer-derived MDSCs could induce a group of PD-1⁻PD-L1⁺ Bregs with immunosuppressive functions. Here, we reported that blocking PD-1/PD-L1 interaction between MDSCs and B cells could reverse the immunosuppressive functions of PD-1⁻PD-L1⁺ Bregs. The activation of PI3K/AKT/NF-κB signaling pathway is essential for PD-1⁻PD-L1⁺ Bregs to exert immunosuppressive effects. MDSCs activated the PI3K/AKT/NF-κB pathway in B cells via the PD-1/PD-L1 axis. Furthermore, inhibition of PD-1/PD-L1 or PI3K/AKT signaling suppressed both tumor growth and the immunosuppressive functions of PD-1⁻PD-L1⁺ Bregs. Dual suppression of PD-1/PD-L1 and PI3K/AKT exerted better antitumor effect. Finally, MDSCs and PD-1⁻PD-L1⁺ Bregs were colocalized in breast cancer tissues and PD-1⁻PD-L1⁺ Bregs were positively correlated with poor prognosis. Thus, MDSC-educated PD-1⁻PD-L1⁺ Bregs and their regulatory mechanisms could contribute to the immunosuppressive tumor microenvironment. Our study proposes a novel mechanism for MDSC-mediated regulation of B cell immunity, which might shed new light on tumor immunotherapy.⁺Subject terms: Breast cancer, Cancer microenvironment     

Myeloid-Derived Suppressor Cells Are Associated with Viral Persistence and Downregulation of TCR ζ Chain Expression on CD8+ T Cells in Chronic Hepatitis C Patients

Myeloid-derived suppressor cells (MDSCs) play an important role in impairing the function of T cells. We characterized MDSCs in two chronic hepatitis C (CHC) cohorts: a cross-sectional group that included 61 treatment-naive patients with CHC, 14 rapid virologic response (RVR) cases and 22 early virologic response (EVR) cases; and a longitudinal group of 13 cases of RVR and 10 cases of EVR after pegylated-interferon-α/ribavirin treatment for genotype 1b HCV infection. Liver samples from 32 CHC patients and six healthy controls were subjected to immunohistochemical analysis. MDSCs frequency in treatment-naive CHC was significantly higher than in RVR, EVR, or healthy subjects and was positively correlated with HCV RNA. Patients infected with HCV genotype 2a had a significantly higher frequency of MDSCs than those infected with genotype 1b. Decreased T cell receptor (TCR) ζ expression on CD8⁺ T cells was significantly associated with an increased frequency of MDSCs in treatment-naive CHC patients and was restored by L-arginine treatment in vitro. Increased numbers of liver arginase-1⁺ cells were closely associated with the histological activity index in CHC. The TCR ζ chain was significantly downregulated on hepatic CD8⁺ T cells in CHC. During antiviral follow up, MDSCs frequency in peripheral blood mononuclear cells was directly correlated with the HCV RNA load in the plasma and inversely correlated with TCR ζ chain expression in CD8⁺ T cells in both RVR and EVR cases. Notably, the RVR group had a higher frequency of MDSCs at baseline than the EVR group. Collectively, this study provides evidence that MDSCs might be associated with HCV persistence and downregulation of CD8 ζ chain expression.     

NKG2D ligand RAE1ε induces generation and enhances the inhibitor function of myeloid‐derived suppressor cells in mice

Expression of surface NKG2D ligands on tumour cells, which activates nature killer (NK) cells and CD8⁺ T cells, is crucial in antitumour immunity. Some types of tumours have evolved mechanisms to suppress NKG2D‐mediated immune cell activation, such as tumour‐derived soluble NKG2D ligands or sustained NKG2D ligands produced by tumours down‐regulate the expression of NKG2D on NK cells and CD8⁺ T cells. Here, we report that surface NKG2D ligand RAE1ε on tumour cells induces CD11b⁺Gr‐1⁺ myeloid‐derived suppressor cell (MDSC) via NKG2D in vitro and in vivo. MDSCs induced by RAE1ε display a robust induction of IL‐10 and arginase, and these MDSCs show greater suppressive activity by inhibiting antigen‐non‐specific CD8⁺ T‐cell proliferation. Consistently, upon adoptive transfer, MDSCs induced by RAE1ε significantly promote CT26 tumour growth in IL‐10‐ and arginase‐dependent manners. RAE1ε moves cytokine balance towards Th2 but not Th1 in vivo. Furthermore, RAE1ε enhances inhibitory function of CT26‐derived MDSCs and promotes IL‐4 rather than IFN‐γ production from CT26‐derived MDSCs through NKG2D in vitro. Our study has demonstrated a novel mechanism for NKG2D ligand⁺ tumour cells escaping from immunosurveillance by facilitating the proliferation and the inhibitory function of MDSCs.     

C-type lectin receptor Dectin3 deficiency balances the accumulation and function of FoxO1-mediated LOX-1+ M-MDSCs in relieving lupus-like symptoms

Recent studies indicate that Toll-like receptors (TLRs) and C-type lectin receptors (CLRs) can function as the signal of pattern recognition receptors, which play a pivotal role in the pathogenesis of the autoimmune disease. Systemic lupus erythematosus (SLE) is a classic autoimmune disease. Previous reports mainly focused on the potential role of TLRs in regulating the development of SLE, but little is known about the role of CLRs in the progression of SLE. Our previous studies showed that the inflammation-mediated accumulation of myeloid-derived suppressor cells (MDSCs) including granulocytic (G-MDSCs) and monocytic (M-MDSCs) participated in the pathogenesis of lupus. Mice deficient in Card9 (the downstream molecule of CLRs) were more susceptible to colitis-associated cancer via promoting the expansion of MDSCs. Whether the abnormal activation of CLRs regulates the expansion of MDSCs to participate in the pathogenesis of lupus remains unknown. In the present study, the expressions of CLRs were examined in both SLE patients and mouse models, revealing the expression of Dectin3 was positively correlated with SLEDAI. Dectin3 deficiency retarded the lupus-like disease by regulating the expansion and function of MDSCs. The mechanistic analysis revealed that Dectin3 deficiency promoted FoxO1-mediated apoptosis of MDSCs. Syk-Akt1-mediated nuclear transfer of FoxO1 increased in Dectin3-deficient MDSCs. Notedly, the accumulation of M-MDSCs mainly decreased in Dectin3^−/− lupus mice, and the nuclear transfer of FoxO1 negatively correlated with the expression of LOX-1 on M-MDSCs. The silencing of FoxO1 expression in Dectin3^−/− mice promoted the expansion of LOX-1⁺ M-MDSCs in vivo, and LOX-1⁺ M-MDSCs increased the differentiation of Th17 cells. Both LOX-1 expression on M-MDSCs and Dectin3 expression on MDSCs increased in patients with SLE. These data indicated that increased LOX-1⁺ M-MDSCs were related to the exacerbation of SLE development and might be potential target cells for the treatment of SLE.Subject terms: Cell signalling, Autoimmunity, Cell death and immune response     

Glycogen synthase kinase 3: a point of convergence for the host inflammatory response

The phosphatidylinositol 3-kinase (PI3K) pathway has been shown to play a central role in regulating the host inflammatory response. Recent studies characterizing the downstream effector molecules within the PI3K pathway have identified that the serine/threonine kinase, glycogen synthase kinase 3 (GSK3), plays a pivotal role in regulating the production of pro- and anti-inflammatory cytokines. In innate immune cells, GSK3 inactivation augments anti-inflammatory cytokine production while concurrently suppressing the production of pro-inflammatory cytokines. The role of GSK3 in T cell biology has also been studied in detail and is involved in regulating multiple downstream signaling processes mediated by the T cell receptor (TCR), the co-stimulatory molecule CD28, and the IL-17 receptor. In vivo studies assessing the therapeutic properties of GSK3 inhibitors have shown that the inactivation of GSK3 can protect the host from immune-mediated pathology and death. This review will highlight the immunological importance GSK3 plays within different signal transduction pathways of the immune system, the cellular mechanisms regulating the activity of GSK3, the role of GSK3 in innate and adaptive immune responses, and the in vivo use of GSK3 inhibitors to treat inflammatory mediated diseases in animals.     

Swertianolin ameliorates immune dysfunction in sepsis via blocking the immunosuppressive function of myeloid-derived suppressor cells

In this study, we studied the long-term proliferation trajectory of myeloid-derived suppressor cells (MDSCs) in murine sepsis model and investigated whether swertianolin could modulate the immunosuppressive function of MDSCs. A murine sepsis model was established by cecal ligation and perforation (CLP), according to the Minimum Quality Threshold in Pre-Clinical Sepsis Studies (MQTiPSS) guidelines. The bone marrow and spleen of the mice were collected at 24 h, 72 h, 7 and 15 d after sepsis induction. The proportions of monocytic- MDSCs (M-MDSCs; CD11b⁺LY6G^–LY6C^hi) and granulocytic-MDSCs (G-MDSC, CD11b⁺ Ly6G⁺ Ly6C^low) were analyzed by flow cytometry. Then, we have investigated whether swertianolin could modulate the immunosuppressive function of MDSCs in in vitro experiments. G-MDSCs and M-MDSCs increased acutely after sepsis with high levels sustained over a long period of time. G-MDSCs were the main subtype identified in the murine model of sepsis with polymicrobial peritonitis. Furthermore, it was found that swertianolin reduced significantly interleukin-10 (IL-10), nitric oxide (NO), reactive oxygen species (ROS), and arginase production in MDSCs, while reducing MDSC proliferation and promoting MDSC differentiation into dendritic cells. Swertianolin also improved T-cell activity by blocking the immunosuppressive effect of MDSCs. Both subsets of MDSCs significantly increased in the bone marrow and spleen of the mice with sepsis, with GMDSCs being the main subtype identified. Swertianolin effectively regulated the functions of MDSCs and reduced immune suppression.Key words: Sepsis, myeloid-derived suppressor cells (MDSCs), immunosuppression, swertianolin     

Glycogen Synthase Kinase 3 influences cell motility and chemotaxis by regulating PI3K membrane localization in Dictyostelium

Glycogen Synthase Kinase 3 (GSK3) is a multifunctional kinase involved in diverse cellular activities such as metabolism, differentiation, and morphogenesis. Recent studies showed that GSK3 in Dictyostelium affects chemotaxis via TorC2 pathway and Daydreamer. Now we report that GSK3 affects PI3K membrane localization, of which the mechanism has remained to be fully understood in Dictyostelium. The membrane localization domain (LD) of Phosphatidylinositol‐3‐kinase 1 (PI3K1) is phosphorylated on serine residues in a GSK3 dependent mechanism and PI3K1‐LD exhibited biased membrane localization in gsk3^? cells compared to the wild type cells. Furthermore, multiple GSK3‐phosphorylation consensus sites exist in PI3K1‐LD, of which phosphomimetic substitutions restored cAMP induced transient membrane localization of PI3K1‐LD in gsk3^? cells. Serine to alanine substitution mutants of PI3K1‐LD, in contrast, displayed constitutive membrane localization in wild type cells. Biochemical analysis revealed that GSK3 dependent serine phosphorylation of PI3K1‐LD is constitutive during the course of cAMP stimulation. Together, these data suggest that GSK3 dependent serine phosphorylation is a prerequisite for chemoattractant cAMP induced PI3K membrane localization.     

Tonsil-derived mesenchymal stem cells alleviate concanavalin A-induced acute liver injury

Acute liver failure, the fatal deterioration of liver function, is the most common indication for emergency liver transplantation, and drug-induced liver injury and viral hepatitis are frequent in young adults. Stem cell therapy has come into the limelight as a potential therapeutic approach for various diseases, including liver failure and cirrhosis. In this study, we investigated therapeutic effects of tonsil-derived mesenchymal stem cells (T-MSCs) in concanavalin A (ConA)- and acetaminophen-induced acute liver injury. ConA-induced hepatitis resembles viral and immune-mediated hepatic injury, and acetaminophen overdose is the most frequent cause of acute liver failure in the United States and Europe. Intravenous administration of T-MSCs significantly reduced ConA-induced hepatic toxicity, but not acetaminophen-induced liver injury, affirming the immunoregulatory capacity of T-MSCs. T-MSCs were successfully recruited to damaged liver and suppressed inflammatory cytokine secretion. T-MSCs expressed high levels of galectin-1 and -3, and galectin-1 knockdown which partially diminished interleukin-2 and tumor necrosis factor α secretion from cultured T-cells. Galectin-1 knockdown in T-MSCs also reversed the protective effect of T-MSCs on ConA-induced hepatitis. These results suggest that galectin-1 plays an important role in immunoregulation of T-MSCs, which contributes to their protective effect in immune-mediated hepatitis. Further, suppression of T-cell activation by frozen and thawed T-MSCs implies great potential of T-MSC banking for clinical utilization in immune-mediated disease.     

Gansui-Banxia Decoction extraction inhibits MDSCs accumulation via AKT /STAT3/ERK signaling pathways to regulate antitumor immunity in C57bl/6 mice

BackgroundGansui-Banxia Decoction (GSBXD) is a classic formula of traditional Chinese medical (TCM) sage Zhang Zhongjing to treat stagnation of evil heat and obstruction of qi. At present GSBXD is wildly used to treat cancerous ascites, pleural effusion, peritoneal effusion, pericardial effusion, cranial cavity effusion and several types of cancers, such as hepatocellular carcinoma (HCC) and esophageal cancer. Myeloid-derived suppressor cells (MDSCs) are a kind of immature and heterogeneous cells which can suppress lymphocytes activation by forming a suppressive environment. MDSCs accumulation in peripheral blood and tumors are closely related to the cancer stage and low survival rate of clinical patients. The antitumor immune effect of GSBXD has not received widespread attention.PurposeTo investigate the effects of GSBXD on MDSCs accumulation and the mediators including AKT/STAT3/ERK signaling pathways.MethodsThe chemical components of GSBXD were analyzed by UHPLC-MS, and the putative pathways of GSBXD based on Network pharmacology were predicted. Mice were vaccinated with Hepatoma 22 (H22) to establish tumor growth model, which were then administrated with GSBXD ethanol extraction (0.49 mg/kg/day, 1.75 mg/kg/day), sorafenib (60 mg/kg) or saline for 14 days. The cell morphology was evaluated by hematoxylin and eosin (H&E) staining, and immunity cells were determined through flowcytometry analysis. The levels of cytokines production in blood were evaluated by using ELISA kits. STAT3, ERK and AKT/mTOR signaling transduction associated proteins were determined by Western blot.ResultsGSBXD could inhibit tumor growth and splenomegaly in H22 tumor model mice. Importantly, GSBXD reduced MDSCs accumulation and differentiation, and inhibited proliferation of F4/80⁺ CD11b⁺ macrophages and apoptosis of T cells and B cells, and increased the percentage of CD 3⁻ NK1.1⁺ NK cells. To better understand the active component of GSBXD, the ethanol-extraction powdered GSBXD was prepared and analyzed by UHPLC-MS. Combined with these main chemical compounds, we predicted that the anti-tumor effect of GSBXD mainly mediated PI3K-AKT and RAS-MAPK signal pathways based on Network Pharmacology. Western blot analysis of tumor tissues and MDSCs cells demonstrated that phosphorylation of AKT, ERK and STAT3 were significantly reduced, specially the activation of ERK. The levels of IL-1β and IFN-γ were significantly decreased by ELISA analysis.ConclusionGSBXD exhibited antitumor immune activity by reducing the accumulation of MDSCs in vivo, which is possible via down-regulation of AKT/STAT3/ERK signaling pathway and suppression of IL-1β and IFN-γ.     

Myeloid-Derived Suppressor Cells in Murine Retrovirus-Induced AIDS Inhibit T- and B-Cell Responses In Vitro That Are Used To Define the Immunodeficiency

Myeloid-derived suppressor cells (MDSCs) have been characterized in several disease settings, especially in many tumor systems. Compared to their involvement in tumor microenvironments, however, MDSCs have been less well studied in their responses to infectious disease processes, in particular to retroviruses that induce immunodeficiency. Here, we demonstrate for the first time the development of a highly immunosuppressive MDSC population that is dependent on infection by the LP-BM5 retrovirus, which causes murine acquired immunodeficiency. These MDSCs express a cell surface marker signature (CD11b⁺ Gr-1⁺ Ly6C⁺) characteristic of monocyte-type MDSCs. Such MDSCs profoundly inhibit immune responsiveness by a cell dose- and substantially inducible nitric oxide synthase (iNOS)-dependent mechanism that is independent of arginase activity, PD-1–PD-L1 expression, and interleukin 10 (IL-10) production. These MDSCs display levels of immunosuppressive function in parallel with the extent of disease in LP-BM5-infected wild-type (w.t.) versus knockout mouse strains that are differentially susceptible to pathogenesis. These MDSCs suppressed not only T-cell but also B-cell responses, which are an understudied target for MDSC inhibition. The MDSC immunosuppression of B-cell responses was confirmed by the use of purified B responder cells, multiple B-cell stimuli, and independent assays measuring B-cell expansion. Retroviral load measurements indicated that the suppressive Ly6G^low/± Ly6C⁺ CD11b⁺-enriched MDSC subset was positive for LP-BM5, albeit at a significantly lower level than that of nonfractionated splenocytes from LP-BM5-infected mice. These results, including the strong direct MDSC inhibition of B-cell responsiveness, are novel for murine retrovirus-induced immunosuppression and, as this broadly suppressive function mirrors that of the LP-BM5-induced disease syndrome, support a possible pathogenic effector role for these retrovirus-induced MDSCs.