Transfer Of Myeloid-derived Suppressor Cells Research Articles

Dexamethasone promotes renal fibrosis by upregulating ILT4 expression in myeloid-derived suppressor cells.

Studies have shown that adoptive transfer of myeloid-derived suppressor cells (MDSCs) can alleviate various inflammatory diseases, including glomerulonephritis, but the long-term effects of the transferred MDSCs are still unclear. In addition, although glucocorticoids exert immunosuppressive effects on inflammatory diseases by inducing the expansion of MDSCs, the impact of glucocorticoids on the immunosuppressive function of MDSCs and their molecular mechanisms are unclear. In this study, we found that adoptive transfer of MDSCs to doxorubicin-induced focal segmental glomerulosclerosis (FSGS) mice for eight consecutive weeks led to an increase in serum creatinine and proteinuria and aggravation of renal interstitial fibrosis. Similarly, 8 weeks of high-dose dexamethasone administration exacerbated renal interstitial injury and interstitial fibrosis in doxorubicin-induced mice, manifested as an increase in serum creatinine and proteinuria, collagen deposition and α-SMA expression. On this basis, we found that dexamethasone could enhance MDSC expression and secretion of the fibrosis-related cytokines TGF-β and IL-10. Mechanistically, we revealed that dexamethasone promotes the expression of immunoglobulin-like transcription factor 4 (ILT4), which enhances the T-cell inhibitory function of MDSCs and promotes the activation of STAT6, thereby strengthening the expression and secretion of TGF-β and IL-10. Knocking down ILT4 alleviated renal fibrosis caused by adoptive transfer of MDSCs. Therefore, our findings demonstrate that the role and mechanism of dexamethasone mediate the expression and secretion of TGF-β and IL-10 in MDSCs by promoting the expression of ILT4, thereby leading to renal fibrosis.

Maternal circadian rhythm disruption affects neonatal inflammation via metabolic reprograming of myeloid cells.

Disruption of circadian rhythm during pregnancy produces adverse health outcomes in offspring; however, the role of maternal circadian rhythms in the immune system of infants and their susceptibility to inflammation remains poorly understood. Here we show that disruption of circadian rhythms in pregnant mice profoundly aggravates the severity of neonatal inflammatory disorders in both male and female offspring, such as necrotizing enterocolitis and sepsis. The diminished maternal production of docosahexaenoic acid (DHA) and the impaired immunosuppressive function of neonatal myeloid-derived suppressor cells (MDSCs) contribute to this phenomenon. Mechanistically, DHA enhances the immunosuppressive function of MDSCs via PPARγ-mediated mitochondrial oxidative phosphorylation. Transfer of MDSCs or perinatal supplementation of DHA relieves neonatal inflammation induced by maternal rhythm disruption. These observations collectively demonstrate a previously unrecognized role of maternal circadian rhythms in the control of neonatal inflammation via metabolic reprograming of myeloid cells.

Monocytic MDSCs skew Th17 cells toward a pro-osteoclastogenic phenotype and potentiate bone erosion in rheumatoid arthritis.

While myeloid-derived suppressor cells (MDSCs) were previously shown to promote a proinflammatory T helper (Th) 17 response in autoimmune conditions, a potential impact of the MDSC-Th17 immune axis on abnormal bone destruction in RA remains largely unknown. We investigated the correlation between the frequency of MDSCs or its subsets and joint destruction in RA patients. The reciprocal actions of patient-derived MDSCs and Th17 cells were studied using osteoclast (OC) differentiation and bone resorption assays in vitro, which were further validated using mouse models of RA. Contribution of MDSCs to osteoclastogenesis and bone erosion in vivo was determined by depletion or transfer of MDSCs. Human MDSCs, particularly monocytic MDSCs (M-MDSCs), exhibit inherent OC-differentiating capacity and positively correlate with clinical bone erosion in RA patients. Strikingly, patient-derived M-MDSCs can program Th17 cells towards a pro-osteoclastogenic phenotype, which in return potentiates OC differentiation via the receptor activator of nuclear factor κΒ ligand (RANK-L)-RANK signalling. This enhanced osteolysis driven by the reciprocal actions of M-MDSCs and Th17 cells is further confirmed using mouse models of RA. Selective depletion of M-MDSCs significantly ameliorates osteoclastogenesis and disease severity in arthritic mice, whereas transfer of M-MDSCs aggravates bone erosion associated with increased OCs in recipient mice. Our findings highlight the functional plasticity of MDSCs and identify a novel pro-osteoclastogenic pathway governed by interplay between myeloid cells and T lymphocytes in autoimmune RA.

Myeloid-derived suppressor cells exacerbate Sjögren’s syndrome by inhibiting Th2 immune responses

Myeloid-derived suppressor cells (MDSCs) can regulate various aspects of immune responses based on their potent immune-suppressive activity. Studies reported that MDSCs participated in many autoimmune diseases. However, the role of MDSCs in Sjögren’s syndrome (SS) is unknown. In this study, we determined the frequencies and function of MDSCs in non-obese diabetic (NOD) mice and SS patients. The NOD mice were adoptively transferred with MDSCs or treated with anti-Gr1 antibody. Results showed that peripheral MDSCs increased significantly with the development of SS-like syndrome in NOD mice and the percentage of MDSCs was higher in SS patients than healthy controls. The SS-like syndrome aggravated after transfer of MDSCs in NOD mice. The deletion of MDSCs in NOD mice alleviated SS-like syndrome. Mechanistically, MDSCs down-regulated the percentages of Th2 cells in NOD mice and SS patients. In summary, our findings suggested that MDSCs exacerbated Sjögren’s syndrome by inhibiting Th2 cells.

Abstract P183: Myeloid-Derived Suppressor Cells Prevent Cyclosporine A-Induced Hypertension, Endothelial Dysfunction, and Renal Injury in Mice

Cyclosporine A (CsA) is an immunosuppressive drug used to treat focal segmental glomerulosclerosis, reduce autoimmune diseases, and prevent allograft rejection; however a limitation of CsA is that it can induce vascular and renal injury as well as hypertension. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature granulocytes, macrophages, and dendritic cells that suppress pro-inflammatory immune responses by secreting anti-inflammatory cytokines, inhibiting innate and adaptive immune cells, and inducing regulatory T cells (Tregs). We hypothesized that adoptive transfer of MDSCs would prevent CsA-induced vascular and renal injury and hypertension. Daily treatment of male C57BL6/J mice for 1 week with CsA (50 mg/kg/day, i.p. injection) significantly increased systolic blood pressure (Day 7 SBP in mmHg: Con=97±2 vs. CsA=145±3, p<0.05 vs. Con), decreased aortic endothelium-dependent relaxation responses, increased aortic fibronectin levels, increased renal glomerular mesangial expansion, increased renal fibronectin levels, and decreased splenic Treg levels. Adoptive transfer of 1 million MDSCs by i.p. injection on days 1, 4, and 7 partially prevented the CsA-induced rise in systolic blood pressure (CsA+1M MDSCs=120±3 mmHg) and the detrimental vascular and renal effects. However, adoptive transfer of 2 million MDSCs fully prevented the CsA-induced hypertension (CsA+2M MDSCs=105±1 mmHg) and vascular and renal effects. The anti-hypertensive and vascular and renal protective effects of 2 million MDSCs were independent of Treg induction as splenic Treg levels remained significantly decreased. These data suggest that MDSCs can prevent the hypertension and toxicity caused by CsA independent of Tregs and may be a therapeutic target for CsA-treated patients.

Adoptive Transfer of Myeloid-Derived Suppressor Cells and T Cells in a Prostate Cancer Model.

The adoptive transfer of immune cells for cancer, chronic infection, and autoimmunity is an emerging field that has shown promise in recent trials. The transgenic adenocarcinoma mouse prostate (TRAMP) is a classical mouse model of prostate cancer (PCa) and TRAMP cell lines were derived from a TRAMP mouse tumor. TRAMP-C2 is tumorigenic when subcutaneously (s.c.) grafted into syngeneic C57BL/6 host mice (Foster et al., 1997). This protocol will describe the adoptive transfer of purified CD11b+Gr1+ double positive (DP) myeloid-derived suppressor cells (MDSC) and CD3+ T cells in the TRAMP-C2 prostate cancer mouse model in order to establish the intrinsic functionality of these immune cells and to determine their role in tumorigenesis in vivo (Yan et al., 2014).

Abstract 258: The Compensatory Effect Of An Increased Body Of Myeloid-derived Suppressor Cells In Hypertension

The immune system plays a critical role in hypertension progression. It has been showed that the lack of T cells prevented the development of hypertension. However, the role of myeloid cells in this process is elusive. We now show that there is a 2 fold increase of CD11b+ Gr1+ myeloid cells in murine hypertension models induced by angiotensin II, L-NAME or high salt diet. These increased myeloid cells are immunosuppressive in that they could suppress T cell proliferation. The production of reactive oxygen species mediates their immunosuppressive functions. When hypertensive mice were depleted of these myeloid cells, using either anti-Gr1 antibody or gemcitabine, there was a 15 mmHg further rise in blood pressure and aggravation of T cell activation as manifested by increased production of IFN-γ, TNFα and IL-17 in both spleen and kidney. In contrast, adoptive transfer of myeloid-derived suppressor cells could be used as both treatment reagent to alleviate established hypertension and preventive reagent from hypertensive insult. These data unveil the role of a distinctive myeloid population in hypertension, which may be a potential target for hypertension management.

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 ConA-mediated 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.

Passive Transfer of Tumour‐Derived MDSCs Inhibits Asthma‐Related Airway Inflammation

Myeloid-derived suppressor cells (MDSCs), a heterogeneous population including myeloid progenitor and immature myeloid cells, are known to inhibit T cell responses. The issue of whether tumour-derived MDSCs regulate the immune response in an asthma environment is currently unclear. Here, we have reported that tumour-derived MDSCs shift the balance back to normal in a Th2-dominant asthmatic environment. In an ovalbumin (OVA)-induced mouse asthma model, injected tumour-derived MDSCs were recruited to the lungs of asthmatic mice by CC chemokine ligand 2 (CCL2). MDSCs transferred into asthmatic mice via i.v. injection suppressed the infiltration of inflammatory cells into the lung, the Th2 cytokine, IL-4, concentration in bronchial lavage fluid and the serum level of OVA-specific IgE. Increased TGF-β1 production in the lung was detected after transfer of MDSCs. The inhibitory effects of MDSCs were reversed upon treatment with an anti-TGF-β1 antibody, suggesting dependence of these activities on TGF-β1. Our findings imply that tumour-derived MDSCs inhibit the Th2 cell-mediated response against allergen in a TGF-β1-dependent manner. Based on the collective results, we propose that asthma may be effectively targeted using a novel MDSC-based cell therapy approach.

Abstract 87: The Accumulation of Myeloid-derived Suppressor Cells Is a Compensatory Response to the Development of Hypertension

The immune system plays a critical role in the development of hypertension. The immune response consists of pro-inflammatory cells, but also immunosuppressive cells that reduce T cell function. An important category of natural immunosuppressive cell is myeloid-derived suppressor cells (MDSC). We now show that blood and spleen CD11b+ Gr1+ myeloid cells are elevated 2-fold in both angiotensin II and L-NAME induced hypertension. These increased myeloid cells are MDSC in that they elevate IL-4R expression and suppress T cell proliferation. When hypertensive mice were depleted of MDSC, using either anti-Gr1 antibody or gemcitabine, there was a 15 mmHg rise in blood pressure and aggravation of T cells activation with increased production of IFN-γ, TNFα and IL-17 in both spleen and kidney. In contrast, adoptive transfer of MDSC reduced blood pressure in angiotensin-II induced hypertension by 25 mmHg (see Figure). These data suggest a new concept, that the accumulation of MDSC is a compensatory response to the inflammation induced by hypertension. They also indicate that MDSC play an important role in regulating blood pressure.

Mast Cell–deficient KitW-sh “Sash” Mutant Mice Display Aberrant Myelopoiesis Leading to the Accumulation of Splenocytes That Act as Myeloid-Derived Suppressor Cells

Mast cell-deficient Kit(W-sh) "sash" mice are widely used to investigate mast cell functions. However, mutations of c-Kit also affect additional cells of hematopoietic and nonimmune origin. In this study, we demonstrate that Kit(W-sh) causes aberrant extramedullary myelopoiesis characterized by the expansion of immature lineage-negative cells, common myeloid progenitors, and granulocyte/macrophage progenitors in the spleen. A consistent feature shared by these cell types is the reduced expression of c-Kit. Populations expressing intermediate and high levels of Ly6G, a component of the myeloid differentiation Ag Gr-1, are also highly expanded in the spleen of sash mice. These cells are able to suppress T cell responses in vitro and phenotypically and functionally resemble myeloid-derived suppressor cells (MDSC). MDSC typically accumulate in tumor-bearing hosts and are able to dampen immune responses. Consequently, transfer of MDSC from naive sash mice into line 1 alveolar cell carcinoma tumor-bearing wild-type littermates leads to enhanced tumor progression. However, although it can also be observed in sash mice, accelerated growth of transplanted line 1 alveolar cell carcinoma tumors is a mast cell-independent phenomenon. Thus, the Kit(W-sh) mutation broadly affects key steps in myelopoiesis that may have an impact on mast cell research.

Abstract 413: Involvement of myeloid derived suppressor cells (MDSC) in the changes of plasma amino acid profiles in cancer disease

Abstract Although maintained in healthy human, it is well known that plasma amino acid profiles are changed in various pathologic conditions, including liver disorder and cancer. We have previously reported the potential use of plasma amino acid profiling as diagnosis for several cancer disease. However, some questions remained for the mechanisms. The changes in plasma amino acid profiles in tumor disease were regulated by a lot of factors, including metabolic changes of tumors and immune cells. In this study, we focused on the role of immune cells, especially myeloid derived suppressor cells (MDSC). MDSC are characterized as immature myeloid cells that are precursors of dendritic cells, macrophages, and/or granulocytes, they are considered to accumulate in the blood, lymph nods, and at tumor sites in most patients and experimental animals with cancer and inhibit anti-tumor inflammation. Therefore we hypothesized that MDSC were involved in the changes in plasma amino acid profiles in tumor disease. To test our hypothesis, we employed C57BL/6 mice tumor model in which Lewis lung carcinoma (3LL) was injected subcutaneously. Using flow cytometry analysis, a significant percentage of MDSC were detected in spleens of tumor-bearing mice as compared to control normal mice. To assess the role of MDSC in the changes in plasma amino acid profile, we eliminated MDSC from the tumor-bearing mice by inducing apoptosis cell death on MDSC selectively in vivo. Flow cytometry results showed a significant decrease in the percentage of CD11b+ Gr1+ cells in splenocytes derived from MDSC deleted tumor-bearing mice as compared to tumor-bearing mice. To study the immunogenic effects of the MDSC deletion on the tumor-bearing mice, we performed histological analysis (H&E staining) and extensive areas of inflammation within 3LL subcutaneous tumors were observed after the MDSC deletion. In addition, we investigated the effects of the MDSC deletion on the percentage of splenic T cell subpopulations by Flow cytometry. The percentage of CD4+ and CD8+ T cells were increased in spleens of MDSC deleted tumor-bearing mice compared to untreated tumor-bearing mice. To evaluate the effects of the MDSC depletion on the plasma amino acid profiles, plasma samples were collected from normal mice, tumor-bearing mice, and MDSC deleted tumor-bearing mice. Plasma amino acid concentration were measured by LC-MS. The MDSC deletion significantly changed the concentrations of some amino acids in plasma compared to the untreated tumor-bearing mice and normal mice. These changes in plasma amino acid concentrations were partially impeded by adoptive transfer of MDSC from tumor-bearing mice. Altogether, these results suggest that MDSC may be involved in the changes in plasma amino acid profiles in tumor disease. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 413. doi:10.1158/1538-7445.AM2011-413

Abstract B52: Characterizing the MDSCs phenotypes, expansion, and trafficking pattern and associated tumor-induced immune dysfunction

Abstract Among the prerequisites to be effective, immunotherapy must work in the presence of the host immunosuppression. Myeloid-derived suppressor cells (MDSCs) are one of the cellular mediators that have a role in limiting the induction of adaptive immune response and host responses to immunotherapy. MDSCs are an immature, heterogeneous cellular population, including hematopoietic precursors for granulocytes, macrophages, dendritic cells, and endothelial cells. They are infrequent in healthy hosts, but increase during tumor progression as a result of dysregulated myeloid cell expansion and differentiation. Tumor growth is frequently associated with an increased frequency of MDSCs that results in a loss in T-cell number and function through increased ROS and peroxynitrites production and arginase 1 (ARG1) and nitric oxide synthase 2 (NOS-2) upregulation. A better understanding of MDSCs expansion and the regulation of biodistribution and arrest would improve interventional strategies and cancer immunotherapy outcomes. Using five mammary tumor models, we have examined tumor-associated expansion of MDSCs and observed that this occurs in an organ-specific manner. Murine MDSCs can be subdivided into phenotypically and functionally distinct sub-populations according to Gr-1 expression levels; the CD11b+Gr-1 dim MDSCs with monocytic nuclei and strong T-cell suppressive activity, and CD11b+Gr-1bright having ring-shaped nuclei (polymorphonuclear cells) and a lower T-cell suppression profile. These cells can also be subset based on the expression of Ly-6C which is highly expressed on immature, bone marrow-derived cells and combined this Gr-1 expression Our studies revealed a significant increase in the Ly-6Cbright expression on the CD11b+Gr-1dim MDSCs in all organs studied in tumor-bearing mice as compared to non-tumor-bearing mice. In association with the increase in CD11b+Gr-1dimLy-6Cbright cells in the tumor non-parenchymal cells of 4T1 tumor bearing mice, increased transcripts levels of cytokines associated with MDSCs expansion (granulocyte-colony stimulating factor [G-CSF]) and MDSCs-associated immunosuppression (ARG-1, NOS-2, and cyclooxygenase 2 [COX-2]) while lower levels of these cytokines were observed in tumor NPCs from Cl66 tumor-bearing mice and non-tumor-bearing mice. In association with the increase in MDSCs and loss of T-cells in the 4T1 tumor-bearing mice there was a significant decrease in cytokine transcript levels that can enhance immune response (interferon gamma [IFN-γ] and interleukin 12 [IL-12]) from tumor non-parenchymal cells (NPCs) in 4T1 tumor bearing mice as compared to Cl66 tumor bearing mice and non-tumor bearing mice. Studies to assess where the MDSCs were expanding revealed that in 4T1 tumor bearing mice, frequency of the proliferating MDSCs is increased only in the spleen and liver compared to the non-tumor-bearing mice. Our studies also examined the affect of tumor burden on the trafficking of MDSCs. We observed that, after adoptive transfer of MDSCs isolated from 4T1 tumor-bearing mice, they arrest initially within the lungs in non-tumor-bearing mice. While in 4T1 tumor-bearing mice they rapidly transverse the lungs with arrest within the tumor tissue. We and others reported that the increase in MDSCs frequencies is associated with a decrease in CD3+ cells function and numbers. We observed a decrease in frequency of all T-cell subsets in the thymus of tumor bearing mice tested compared to the non-tumor-bearing mice suggesting defects in T-cell maturation associated with tumor burden. We investigated the effect of tumor burden on the phenotype of the CD3+ cells using the Annexin V staining and found that 4T1 tumor bearing mice have increased frequency of Annexin V positive CD3+ T-cells that are infiltrating tumor tissue compared to those in other organs. Citation Information: Clin Cancer Res 2010;16(14 Suppl):B52.