Frequency Of Myeloid-derived Suppressor Cells Research Articles

Nitric oxide-producing monocyte-myeloid suppressor cells expand and accumulate in the spleen and mesenteric lymph nodes of Yersinia enterocolitica-infected mice

IntroductionYersinia enterocolitica (Ye) is a Gram-negative bacterium that causes gastrointestinal infections. The myeloid-derived suppressor cells (MDSCs) constitute a cellular population with the capacity of inducing the specific suppression of T cells. Although there is evidence supporting the role of MDSCs in controlling the immune responses in several bacterial infections, its role during Ye infection has not yet been reported. Therefore, the purpose of the present work was to analyze MDSCs after oral Ye infection.MethodsC57BL/6 wild-type mice were infected with Ye WAP-314 serotype O:8. The proliferation of splenocytes and mesenteric lymph nodes (MLN) cells was measured as well as the levels of cytokines and nitric oxide (NO) in culture supernatants. The frequency and subsets of MDSCs were analyzed in the intestinal mucosa and spleen by flow cytometry. Furthermore, monocytic-MDSCs (Mo-MDSCs) and polymorphonuclear-MDSCs (PMN-MDSCs) were purified from the spleen of infected mice and their suppressor activity was evaluated in co-cultures with purified T cells.Resultswe observed a marked expansion of CD11b+Gr-1+ cells, a phenotype consistent with MDSCs, in the spleen and intestinal mucosa of Ye-infected mice. Interestingly, a robust proliferation of splenocytes and MLN cells was observed only when the MDSCs were depleted or the NO production was blocked. In addition, we determined that only Mo-MDSCs had the ability to suppress T-cell proliferation.ConclusionOur results highlight a mechanism by which Ye may induce suppression of the immune responses. We suggest that NO-producing Mo-MDSCs expand and accumulate in MLN and spleen of Ye-infected mice. These cells can then suppress the T-cell function without interfering with the anti-bacterial effector response. Instead, these immature myeloid cells may perform an important function in regulating the inflammatory response and protecting affected tissues.

Administration of rIL-33 Restores Altered mDC/pDC Ratio, MDSC Frequency, and Th-17/Treg Ratio during Experimental Cerebral Malaria.

The onset of malaria causes the induction of various inflammatory markers in the host's body, which in turn affect the body's homeostasis and create several cerebral complications. Polarization of myeloid-derived suppressor cells (MDSCs) from the classically activated M1 to alternatively activated M2 phenotype increases the secretion of pro-inflammatory molecules. Treatment with recombinant IL-33 (rIL-33) not only alters this MDSC's polarization but also targets the glycolysis pathway of the metabolism in MDSCs, rendering them less immunosuppressive. Along with that, the Helper T-cells subset 17 (Th17)/T regulatory cells (Tregs) ratio is skewed towards Th17, which increases inflammation by producing more IL-17. However, treating with rIL-33 also helps to restore this ratio, which brings back homeostasis. During malaria infection, there is an upregulation of IL-12 production from dendritic cells along with a distorted myeloid dendritic cells (mDC)/plasmacytoid dendritic cells (pDC) ratio towards mDCs promoting inflammation. Administering rIL-33 will also subvert this IL-12 production and increase the population of pDC in the host's immune system during malaria infection, thus restoring mDC/pDC to homeostasis. Therefore, treatment with rIL-33 to reduce the pro-inflammatory signatures and maintenance of immune homeostasis along with the increase in survivability could be a potential therapeutic approach for cerebral malaria.

Impact of Microparticle Transarterial Chemoembolization (mTACE) on myeloid-derived suppressor cell subtypes in hepatocellular carcinoma: Clinical correlations and therapeutic implications.

Myeloid-derived suppressor cells (MDSCs) play a pivotal role in immunosuppression and tumor progression in hepatocellular carcinoma (HCC). While various treatments like surgical resection, ablation, and radiotherapy have been studied for their effects on circulating MDSC frequencies in HCC patients, the findings remain inconclusive. Transarterial Chemoembolization (TACE) stands as the standard care for unresectable HCC, with Microparticle TACE (mTACE) gaining prominence for its capacity to induce significant tumor necrosis. However, the immunological ramifications of such pathological outcomes are scarcely reported. This study aims to elucidate the alterations in MDSC subtypes, specifically monocytic MDSCs (mMDSCs) and early-stage MDSCs (eMDSCs), post-mTACE and to investigate their clinical correlations in HCC patients. A cohort comprising 75 HCC patients, 16 liver cirrhosis patients, and 20 healthy controls (HC) was studied. Peripheral blood samples were collected and analyzed for MDSC subtypes. The study also explored the associations between MDSC frequencies and various clinical parameters in HCC patients. The frequency of mMDSCs was significantly elevated in the HCC group compared to liver cirrhosis and HC. Importantly, mMDSC levels were strongly correlated with aggressive clinical features of HCC, including tumor size, vascular invasion, and distant metastasis. Post-mTACE, a marked reduction in mMDSC frequencies was observed, while eMDSC levels remained stable. Our findings underscore the critical role of mMDSCs in HCC pathogenesis and their potential as a therapeutic target. The study also highlights the efficacy of mTACE in modulating the immunosuppressive tumor microenvironment, thereby opening new avenues for combinatorial immunotherapeutic strategies in HCC management.

Irreversible electroporation of localised prostate cancerdownregulates immune suppression andinduces systemic anti-tumour T-cell activation - IRE-IMMUNO study.

To prospectively compare systemic anti-tumour immune responses induced by irreversible electroporation (IRE) and robot-assisted radical prostatectomy (RARP) in patients with localised intermediate-risk prostate cancer (PCa). Between February 2021 and June 2022, before and after treatment (at 5, 14 and 30 days) peripheral blood samples of 30 patients with localised PCa were prospectively collected. Patient inclusion criteria were: International Society of Urological Pathologists Grade 2-3, clinical cancer stage ≤T2c, prostate-specific antigen level <20 ng/mL). Patients were treated with IRE (n = 20) or RARP (n = 10). Frequency and activation status of lymphocytic and myeloid immune cell subsets were determined using flow cytometry. PCa-specific T-cell responses to prostatic acid phosphatase(PSAP) and cancer testis antigen (New York oesophageal squamous cell carcinoma 1 [NY-ESO-1]) were determined by interferon-γ enzyme-linked immunospot assay (ELISpot). Repeated-measures analysis of variance and two-sided Student's t-tests were used to compare immune responses over time and between treatment cohorts. Patient and tumour characteristics were similar between the cohorts except for age (median 68 years [IRE] and 62 years [RARP], P = 0.01). IRE induced depletion of systemic regulatory Tcells (P = 0.0001) and a simultaneous increase in activated cytotoxic T-lymphocyte antigen 4 (CTLA-4)+ cluster of differentiation (CD)4+ (P < 0.001) and CD8+ (P = 0.032) Tcells, consistent with reduction of systemic immune suppression allowing for effector T-cell activation, peaking 14 days after IRE. Effects were positively correlated with tumour volume/ablation size. Accordingly, IRE induced expansion of PSAP and/or NY-ESO-1 specific T-cell responses in four of the eight immune competent patients. Temporarily increased activated myeloid derived suppressor cell frequencies (P = 0.047) were consistent with transient immunosuppression after RARP. Irreversible electroporation induces a PCa-specific systemic immune response in patients with localised PCa, aiding conversion of the tumour microenvironment into a more immune permissive state. Therapeutic efficacy might be further enhanced by combination with CTLA-4 checkpoint inhibition, potentially opening up a new synergistic treatment paradigm for high-risk localised or (oligo)metastatic disease.

17β-estradiol promotes myeloid-derived suppressor cells functions and alleviates inflammatory bowel disease by activation of Stat3 and NF-κB signalings

Inflammatory bowel disease (IBD) describes a group of clinically common autoimmune diseases characterized by chronic intestinal inflammation, with gender differences in prevalence. Estrogen has been previously shown to exert anti-inflammatory action in IBD development, however, the mechanisms remain obscure. Recent research has revealed that myeloid-derived suppressor cells (MDSCs) play a protective role in IBD pathogenesis. To investigate the molecular mechanisms of estrogen steroid 17β-estradiol (E2) in IBD progression, we established IBD mouse models (DNB-induced) with or without prior ovariectomy (OVX) and E2 implantation. We found that OVX led to worse IBD symptoms and reduced MDSCs frequency, whereas E2 significantly alleviated these effects in vivo. Moreover, in vitro experiments showed that E2 promoted the proliferation and immunosuppressive function of MDSCs through phosphorylation of Stat3 and p65. Mechanistically, E2-mediated Stat3/p65 phosphorylation depends on the interaction between HOTAIR, a long non-coding RNA that are well-known in MDSCs proliferation, and Stat3/p65 respectively. In conclusion, our study revealed that E2 promotes the expansion and immunosuppressive function of MDSCs, and thus diminished the occurrence and development of IBD.

MDSC expansion during HIV infection: regulators, ART and immune reconstitution.

Myeloid-derived suppressor cells (MDSCs) become expanded in different pathological conditions including human immunodeficiency virus (HIV) infection and this may worsen the disease status and accelerate disease progression. In HIV infection, MDSCs suppress anti-HIV immune responses and hamper immune reconstitution. Understanding the factors and mechanisms of MDSC expansion during HIV infection is central to understanding the pathophysiology of HIV infection. This may pave the way to developing new therapeutic targets or strategies. In this work we addressed (i) the mechanisms that regulate MDSC expansion, (ii) the impact of antiretroviral therapy (ART) on the frequency of MDSCs during HIV infection; (iii) the impact of MDSCs on immune reconstitution during successful ART; and (iv) the potential of MDSCs as a therapeutic target.

Abstract 6530: TREM1 inhibition: A novel approach to suppress tumor growth and enhance immune checkpoint therapy

Abstract In the context of cancer, inflammation is a multifaceted contributor to tumorigenesis. The Triggering Receptor Expressed on Myeloid Cells 1 (TREM1) is recognized for its role in amplifying inflammatory responses, yet its specific pro-tumorigenic mechanisms have remained elusive. This study employs Trem1-deficient mice and a novel inhibitor, VJDT, to explore the therapeutic potential of targeting TREM1 in cancer. Both genetic silencing and pharmacological inhibiton of Trem1 led to remarkable reductions in tumor growth in mouse models of melanoma (B16F10) and fibrosarcoma (MCA205). In-depth analysis using single-cell RNA sequencing unveiled that TREM1 deficiency resulted in a decrease in the frequency and suppressive capabilities of myeloid-derived suppressor cells (MDSCs) within the tumor microenvironment, concomitant with an increase in cytotoxic CD8+ T cells and enhanced T cell activation. Furthermore, TREM1 inhibition not only curtailed tumor growth but also potentiated the effectiveness of anti-PD-1 therapy, primarily by mitigating MDSC frequency and reversing T cell exhaustion. Notably, in melanoma xenografts from patient samples, pharmacological TREM1 inhibition via VJDT treatment significantly downregulated critical oncogenic pathways linked to cell proliferation, migration, and survival. This research underscores the pivotal role of TREM1, expressed both within cancer cells and the tumor microenvironment, in driving cancer progression. Consequently, targeting TREM1 for therapeutic intervention holds promise for reshaping the immunosuppressive tumor milieu and augmenting the success of immune checkpoint therapy. Citation Format: Ashwin Ajith, Kenza Moamouni, Daniel D Horuzsko, Anatolij Horuzsko. TREM1 inhibition: A novel approach to suppress tumor growth and enhance immune checkpoint therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6530.

MCL1 inhibition targets Myeloid Derived Suppressors Cells, promotes antitumor immunity and enhances the efficacy of immune checkpoint blockade

Immune checkpoint inhibitors (ICIs) are now the first-line treatment for patients with advanced melanoma. Despite promising clinical results, many patients fail to respond to these therapies. BH3 mimetics, a novel class of small molecule inhibitors that bind and inhibit anti-apoptotic members of the BCL2 family proteins such as BCL2 or MCL1, have been very successful in treating hematologic malignancies. However, there are limited studies on the immunomodulatory role of the BH3 mimetics. Several factors contribute to ICI resistance including myeloid-derived suppressor cells (MDSCs) that exert immunosuppressive effects through direct and indirect inhibition of antitumor immunity. Thus, targeting MDSCs to enhance antitumor immunity has the potential to enhance the efficacy of ICIs. In this study, we show that the MCL1 inhibitor S64315 reduces melanoma tumor growth in an immune cell-dependent manner in mice. Specifically, S64315 enhances antitumor immunity by reducing MDSC frequency and by promoting the activity of CD8+T cells. Additionally, human MDSCs are 10 times more sensitive to S64315 than cutaneous melanoma lines. Further, we found that a higher expression of MCL1 is associated with poor survival for patients treated with anti-PD-1. Finally, combining S64315 and anti-PD-1 significantly slowed tumor growth compared to either agent alone. Together, this proof-of-concept study demonstrates the potential of combining an MCL1 inhibitor with anti-PD-1 in the treatment of melanoma. It justifies the further development of next generation MCL1 inhibitors to improve efficacy of ICIs in treating malignant melanoma.

Myeloid‑derived suppressor cell accumulation induces Treg expansion and modulates lung malignancy progression.

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous family of myeloid cells that suppress T cell immunity in tumor-bearing hosts. The present study aimed to examine roles of T and MDSC subsets in lung malignancy. The study analyzed 102 cases with lung malignancy and 34 healthy individuals. Flow cytometry was performed for identification of T cell and MDSC subsets and their phenotypic characteristics in peripheral blood. The lung malignancy cases exhibited lower frequencies of granulocyte-like MDSCs (G-MDSCs) expressing PD-L2 and PD-L1 than healthy controls (P=0.013 and P<0.001, respectively). Additionally, there was a higher frequency of monocyte-like MDSCs (M-MDSCs) expressing PD-L1 in the peripheral blood of patients with lung malignancy than healthy controls (P<0.001). The frequencies of G-MDSCs and M-MDSCs were positively correlated with proportions of PD-1+ and CTLA-4+ regulatory T cells (Tregs). In vitro co-culture assay demonstrated M-MDSCs of lung malignancy enhanced naive T cell apoptosis and promoted Treg subset differentiation compared with M-MDSCs of healthy controls. The findings suggested accumulation of MDSC subsets in lung malignancy and MDSCs expressing PD-L2 and PD-L1 induced Treg expansion by binding to PD-1 on the surface of Tregs.

The Immunomodulatory Effects of Fluorescein-Mediated Sonodynamic Treatment Lead to Systemic and Intratumoral Depletion of Myeloid-Derived Suppressor Cells in a Preclinical Malignant Glioma Model.

Fluorescein-mediated sonodynamic therapy (FL-SDT) is an extremely promising approach for glioma treatment, resulting from the combination of low-intensity focused ultrasound (FUS) with a sonosensitizer. In the present study, we evaluated the efficacy and immunomodulation of SDT with fluorescein as the sonosensitizer in immunocompetent GL261 glioma mice for the first time. In vitro studies demonstrated that the exposure of GL261 cells to FL-SDT induced immunogenic cell death and relevant upregulation of MHC class I, CD80 and CD86 expression. In vivo studies were then performed to treat GL261 glioma-bearing mice with FL-SDT, fluorescein alone, or FUS alone. Perturbation of the glioma-associated macrophage subset within the immune microenvironment was induced by all the treatments. Notably, a relevant depletion of myeloid-derived suppressor cells (MDSCs) and concomitant robust infiltration of CD8+ T cells were observed in the SDT-FL-treated mice, resulting in a significant radiological delay in glioma progression and a consequent improvement in survival. Tumor control and improved survival were also observed in mice treated with FL alone (median survival 41.5 days, p > 0.0001 compared to untreated mice), reflecting considerable modulation of the immune microenvironment. Interestingly, a high circulating lymphocyte-to-monocyte ratio and a very low proportion of MDSCs were predictive of better survival in FL- and FL-SDT-treated mice than in untreated and FUS-treated mice, in which elevated monocyte and MDSC frequencies correlated with worse survival. The immunostimulatory potential of FL-SDT treatment and the profound modulation of most immunosuppressive components within the microenvironment encouraged the exploration of the combination of FL-SDT with immunotherapeutic strategies.

Brief Report: In cART-Treated HIV-Infected Patients, Immunologic Failure Is Associated With a High Myeloid-Derived Suppressor Cell Frequency.

During HIV infection, effective combined antiretroviral therapy suppresses viral replication and restores the number of circulating CD4+ T cells. However, 15%-30% of treated patients show a discordant response to combined antiretroviral therapy. Myeloid-derived suppressor cells (MDSC) are expanded in HIV+ patients; to better understand the role of MDSC on CD4 T-cell recovery, we evaluated the frequency of MDSC in HIV+ patients under combined antiretroviral therapy and its association with immunologic response. We enrolled 60 HIV+ patients, including complete responders (R, n = 44), virologic nonresponders (VNR, n = 5), and immunologic nonresponders (INR, n = 11). The frequency of circulating MDSC and the percentage of activated and naïve CD4 T cells were evaluated by flow cytometry. Plasmatic cytokine levels were analyzed by automated ELISA. As previously observed, polymorphonuclear MDSC (PMN-MDSC) frequency was higher in HIV+ patients compared with healthy donors. Furthermore, PMN-MDSC percentage was higher in INR than R patients, and a significant association between MDSC frequency and immunologic failure was confirmed by a receiver operator characteristic analysis. Accordingly, an inverse correlation was found between the percentages of PMN-MDSC and naïve CD4 T cells. A positive correlation was observed between PMN-MDSC frequency and the percentage of human leucocyte antigen locus DR + CD4 T cells and the plasmatic level of IL-1β and IL-8. Our results show that a high frequency of PMN-MDSC persists in INR, possibly because of immune activation, contributing to CD4 T-cell recovery failure. These findings further highlight the detrimental role of MDSC during HIV infection, suggesting these cells as a possible new therapeutic target.

MYELOID-DERIVED SUPPRESSOR CELLS TWO YEARS AFTER HEPATITIS C VIRUS ERADICATION USING DIRECTLY ACTING ANTIVIRALS.

Myeloid-derived suppressor cells (MDSCs) have immature morphology, relatively weak phagocytic activity, as well as some immunosuppressive functions. The capacity of MDSCs to inhibit T-cell-mediated immunological responses is their most notable functional characteristic. Down-regulating antitumor immune surveillance is one way that the expansion and activation of MDSCs contribute significantly to the occurrence and progression of tumors. Increased levels of MDSCs in patients with chronic hepatitis C virus (HCV) infection could suppress T-cell responses, promoting viral escape and hepatitis progression. This may make HCV-infected individuals more vulnerable to severe infections, hepatic and extra-hepatic tumors, and a diminished capacity to react to immunization. It is still unknown if effective HCV eradication with directly acting antivirals (DAAs) can restore immune functions and immune surveillance capacity. The purpose of this study was to observe the frequency of M-MDSCs (CD33+, CD11b+, and HLA-DR) in patients with a previous history of HCV, 2-3 years after virus eradication using DAA therapy. This study was conducted on 110 subjects: fifty-five subjects without liver cirrhosis who were treated with HCV using DAAs and attained SVR for a period of 2-3 years and 55 age- and gender-matched healthy controls. The study was conducted during the period from January to July 2022. Patients were recruited from the National Viral Hepatitis Treatment Unit, Alexandria University Hepatology outpatient clinic, and the Alexandria University Tropical Medicine outpatient clinic. The frequencies of MDSCs (CD33+CD11b + HLA-DR-) by flow cytometry were assessed. Even after the virus had been eradicated for longer than two years, MDSC levels in HCV-treated individuals were found to be considerably higher. In the HCV-treated group, the median number of MDSCs was 5, with an interquartile range (IQR) of 3.79-7.69. In contrast, the median for the control group was 3.1, with an IQR of 1.4-3.2 (P˂0.001). Successful DAA therapy leads to slow and partial immunological reconstitution, as demonstrated by the failure to attain normal levels of MDSC's 2 years after successful HCV eradication despite the normalization of laboratory parameters as well as the absence of liver fibrosis. The clinical implications of these findings should be thoroughly studied.

Triptolide inhibits the proinflammatory potential of myeloid-derived suppressor cells via reducing Arginase-1 in rheumatoid arthritis

Triptolide (TPT) is widely used in the treatment of rheumatoid arthritis (RA). However, its regulatory mechanisms are not fully understood. This study demonstrated that Myeloid-derived suppressor cells (MDSCs) were expanded in both RA patients and arthritic mice. The frequency of MDSCs was correlated with RA disease severity and T helper 17 (Th17) responses. MDSCs from RA patients promoted the polarization of Th17 cells in vitro, which could be substantially attenuated by blocking arginase-1 (Arg-1). TPT inhibited the differentiation of MDSCs, particularly the monocytic MDSCs (M-MDSCs) subsets, as well as the expression of Arg-1 in a dose dependent manner. Alongside, TPT treatment reduced the potential of MDSCs to promote the polarization of IL-17+ T cell in vitro. Consistently, TPT immunotherapy alleviated adjuvant-induced arthritis (AIA) in a mice model, and reduced the frequency of MDSCs, M-MDSCs and IL-17+ T cells simultaneously. The presented data suggest a pathogenic role of MDSCs in RA and may function as a novel and effective therapeutic target for TPT in RA.

Targeting TREM1 augments antitumor T cell immunity by inhibiting myeloid-derived suppressor cells and restraining anti-PD-1 resistance.

The triggering receptor expressed on myeloid cell 1 (TREM1) plays a critical role in development of chronic inflammatory disorders and the inflamed tumor microenvironment (TME) associated with most solid tumors. We examined whether loss of TREM1 signaling can abrogate the immunosuppressive TME and enhance cancer immunity. To investigate the therapeutic potential of TREM1 in cancer, we used mice deficient in Trem1 and developed a novel small molecule TREM1 inhibitor, VJDT. We demonstrated that genetic or pharmacological TREM1 silencing significantly delayed tumor growth in murine melanoma (B16F10) and fibrosarcoma (MCA205) models. Single-cell RNA-Seq combined with functional assays during TREM1 deficiency revealed decreased immunosuppressive capacity of myeloid-derived suppressor cells (MDSCs) accompanied by expansion in cytotoxic CD8+ T cells and increased PD-1 expression. Furthermore, TREM1 inhibition enhanced the antitumorigenic effect of anti-PD-1 treatment, in part, by limiting MDSC frequency and abrogating T cell exhaustion. In patient-derived melanoma xenograft tumors, treatment with VJDT downregulated key oncogenic signaling pathways involved in cell proliferation, migration, and survival. Our work highlights the role of TREM1 in cancer progression, both intrinsically expressed in cancer cells and extrinsically in the TME. Thus, targeting TREM1 to modify an immunosuppressive TME and improve efficacy of immune checkpoint therapy represents what we believe to be a promising therapeutic approach to cancer.

Bushen Antai recipe alleviates embryo absorption by enhancing immune tolerance and angiogenesis at the maternal-fetal interface via mobilizing MDSCs in abortion-prone mice

BackgroundRecurrent pregnancy loss (RPL) is a tricky puzzle that disturbs female reproduction worldwide. According to previous research, Bushen Antai recipe (BAR), a classic Chinese herbal formula widely used in clinic for miscarriage, exhibited multifaceted benefits in improving embryo implantation and attenuating early pregnancy loss. Myeloid-derived suppressor cells (MDSCs), a set of immunoregulatory cells critical in inflammation balance, get growing attention for their indispensable role in successful pregnancy. PurposeTo investigate the therapeutic efficacy of BAR in abortion-prone mice and explore the potential mechanisms of BAR regarding MDSCs. MethodsRPL mice (CBA/J females paired with DBA/2 males, BALB/c males were used as the control) were administered with BAR1 (5.7 g/kg), BAR2 (11.4 g/kg), progesterone (P4), or distilled water from embryo day (D) 0.5 until D10.5. The rate of embryo absorption on D10.5 and the health status of progeny were measured. The systemic inflammatory states and the placenta-uterus milieu were assessed by serum cytokine levels, placenta-uterus architecture, and related protein expression at the maternal-fetal interface. Flow cytometry analysis was carried out to measure the frequency of MDSCs. Furthermore, we established the MDSCs-depletion mouse model by using C57BL/6 females mated with BALB/c males via intraperitoneal injection of anti-Gr-1 antibody on D6.5, while irrelative LTF antibody was used as the control. Similarly, BAR1, BAR2, P4, or distilled water was separately applied. Embryo absorption rate, systemic inflammatory states, placenta-uterus milieu, and MDSCs frequency were evaluated as mentioned above. ResultsSignificantly, embryo absorption rate was increased with disrupted placenta-uterus milieu and exorbitant proinflammatory cytokines in RPL mice, meanwhile, MDSCs number in the placenta-uterus unit were apparently reduced (⁎⁎⁎p < 0.001). BAR treatment markedly alleviated the poor conditions above and increased MDSCs number (####p < 0.0001). Flow cytometry analysis validated the efficacy of anti-Gr-1 antibody and the raised embryo absorption rate confirmed the essentiality of MDSCs in normal pregnancy (⁎⁎p < 0.01). Besides, the placenta-uterus milieu was destroyed, accompanied by the impaired expression of immune tolerance and angiogenesis related factors in the MDSCs-depletion mice. Even though, BAR treatment reversed the embryo resorption phenotype and optimized the serum cytokine milieu, mobilizing MDSCs and rejuvenating active intercellular communication. Thereby, BAR facilitated the expression of MDSCs-related functional molecules, promoting immune tolerance and vascular remodeling at the placenta-uterus unit. ConclusionWe unfurled the remarkable therapeutic ability of BAR in abortion-prone mice, and this was achieved by mobilizing MDSCs, thus favoring immune tolerance and angiogenesis at the maternal-fetal interface.

Effect of External Beam Radiation Therapy (EBRT) and Brachytherapy (BT) on Circulating MDSC Populations in Patients Treated Definitively for Cervical Cancer

The immunosuppressive function of myeloid derived suppressor cells (MDSCs) has been implicated in the regulation of immune responses against cancer. MDSCs have been associated with progression and poor response to therapy in various types of cancer, including cervical cancer. Radiation treatment (RT) alters immune cell populations within the tumor and is thought to augment antitumor responses. However, whether RT also recruits immunosuppressive MDSC populations is not well understood. Here, we investigate how circulating MDSC populations change in response to RT and if changes in MDSC frequency or subsets is predictive of RT responses in cervical cancer patients. Newly diagnosed, treatment-naïve pts with locally advanced carcinoma of the cervix will be enrolled from July 2022 to July 2023. EBRT to the pelvis was delivered at a dose of 45 Gy in 25 fractions with a simultaneous integrated boost of 52-55 Gy to involved regional lymph nodes and parametria and concurrent weekly cisplatin. Gross tumor was boosted via interstitial or tandem ring BT (22.5-27.5 Gy) after completion of EBRT. Serial blood samples were collected prior to initiating therapy (T0), post-EBRT and pre-BT (T1), and one-month post-BT (T2). Treatment response was determined based on pre-treatment MRI compared to MRI post-EBRT. Peripheral blood mononuclear cells (PBMCs) were isolated from whole blood using density gradient centrifugation and stained for analysis via flow cytometry. MDSC populations were identified by Live/Dead-CD11b+CD33+HLA-DR- staining. MDSC subsets were further subdivided into granulocytic (G-, CD15+CD14-), monocytic (M-, CD15-CD14+), or early-MDSCs (e-, CD15-CD14-). Blood samples were collected at indicated time points for four patients (FIGO stage IIA-IIB). Three had partial responses to chemoradiotherapy (CRT), while one had a complete response. All three patients with partial response had an increase in total frequency of circulating MDSCs in response to EBRT/BT (mean %fx MDSC 16.6 at T0 to 35.9 at T2), and an increase in total MDSCs in two of these patients occurred with EBRT alone. Interestingly, the patient that had a complete response had fewer MDSCs at T2 relative to T0 (35.8% at T0 to 27% at T2). Proportion of MDSC subsets varied considerably among the patients, and all had altered distribution of subsets in response to RT. G-MDSCs expanded the most to RT while M-MDSCs and e-MDSCs were less affected (mean fold change from T0 to T2 G-MDSC 4.75, M-MDSC 1.27, e-MDSC 0.942). In this cohort of patients, an increase in MDSC frequency occurred after RT and altered subset distribution. Only the patient with a complete response had fewer total MDSCs following completion of CRT, suggesting further studies are needed to determine if circulating MDSCs could be a biomarker for treatment response to RT in cervical cancer.

DKK-1 and Its Influences on Bone Destruction: A Comparative Study in Collagen-Induced Arthritis Mice and Rheumatoid Arthritis Patients.

Dickkopf-1 (DKK-1) has been considered a master regulator of bone remodeling. As precursors of osteoclasts (OCs), myeloid-derived suppressor cells (MDSCs) were previously shown to participate in the process of bone destruction in rheumatoid arthritis (RA). However, the role of DKK-1 and MDSCs in RA is not yet fully understood. We investigated the relevance between the level of DKK-1 and the expression of MDSCs in different tissues and joint destruction in RA patients and collagen-induced arthritis (CIA) mouse models. Furthermore, the CIA mice were administered recombinant DKK-1 protein. The arthritis scores, bone destruction, and the percentage of MDSCs in the peripheral blood and spleen were monitored. In vitro, the differentiation of MDSCs into OCs was intervened with recombinant protein and inhibitor of DKK-1. The number of OCs differentiated and the protein expression of the Wnt/β-catenin signaling pathway were explored. The level of DKK-1 positively correlates with the frequency of MDSCs and bone erosion in RA patients and CIA mice. Strikingly, recombinant DKK-1 intervention significantly exacerbated arthritis scores and bone destruction, increasing the percentage of MDSCs in the peripheral blood and spleen in CIA mice. In vitro experiments showed that recombinant DKK-1 promoted the differentiation of MDSCs into OCs, reducing the expression of β-catenin and TCF4 and increasing the expression of CyclinD1. In contrast, the DKK-1 inhibitor had the opposite effect. Our findings highlight that DKK-1 promoted MDSCs expansion in RA and enhanced the differentiation of MDSCs into OCs via targeting the Wnt/β-catenin pathway, aggravating the bone destruction in RA.

Hyaluronic acid-bilirubin nanomedicine-based combination chemoimmunotherapy

Despite significant advances in immune checkpoint blockade (ICB), immunosuppression mediated by tumor-associated myeloid cells (TAMCs) poses a major barrier to cancer immunotherapy. In addition, while immunogenic cell death (ICD) provides a viable approach to inducing anti-tumor immune response, it remains unknown how to effectively trigger ICD while addressing immunosuppressive TAMCs. Here, we show that SC144, a gp130 inhibitor that blocks the IL-6/gp130/STAT3 pathway, induces ICD of tumor cells and polarizes macrophages to M1-phenotype in vitro. However, as SC144 also induces killing of CD8+ T-cells, we sought to deliver SC144 selectively to tumor cells and TAMCs. Toward this goal, we have developed hyaluronic acid-bilirubin nanoparticles (HABN) that accumulate in CD44hi tumor cells and TAMCs. Systemic administration of SC144 loaded in HABN (SC144@HABN) induces apoptosis and ICD of tumor cells, increases the ratio of M1-like to M2-like macrophages, and decreases the frequency of myeloid-derived suppressor cells and CD4+ regulatory T-cells, while promoting anti-tumor CD8+ T-cells. Moreover, SC144@HABN combined with anti-PD-L1 ICB efficiently eliminates MC38 tumors and ICB-resistant 4T1 tumors. Overall, our work demonstrates a therapeutic strategy based on coordinated ICD induction and TAMC modulation and highlights the potential of combination chemoimmunotherapy.

Could the Crosstalk Between Myeloid-Derived-Suppressor Cells and Regulatory T Cells Have a Role in Beta-Thalassemia?

Secondary iron overload, alloimmunization, and increased risk of infection are common complications in patients with transfusion-dependent thalassemia (TDT). Regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) play an essential role in preventing excessive immune response. This research aimed to study the interaction between Tregs and MDSCs in TDT patients and to evaluate the association of these cell types with disease severity. This case-control study included 26 patients with TDT and 23 healthy, age- and sex-matched controls. All patients were investigated for complete blood count (CBC), serum ferritin, and flow cytometric analysis of peripheral blood to detect Tregs, MDSCs, and MDSC subsets. A significant increase was observed in the frequencies of Tregs and MDSCs, particularly monocytic MDSCs (MO-MDSCs), in TDT patients compared with controls. The frequencies of these cells showed a direct association with ferritin level and total leukocyte count and an inverse association with hemoglobin level. Furthermore, a positive correlation was observed between Tregs and each of the total MDSCs and MO-MDSCs. Levels of Tregs and MDSCs increased in TDT and may probably have a role in suppressing the active immune systems of TDT patients.

Bushen Antai recipe ameliorates immune microenvironment and maternal-fetal vascularization in STAT3-deficient abortion-prone mice

Ethnopharmacological relevanceSpontaneous abortion (SA) is an intricate disorder affecting women of reproductive age. Previous studies have confirmed the indispensable role of signal transducer and activator of transcription (STAT) 3 in normal pregnancy. Bushen Antai recipe (BAR) is a satisfactory formula commonly used in practice, based on the rationale of traditional Chinese medicine (TCM) for SA. Aim of the studyThe current study explores the potential therapeutic effects and mechanistic insights of BAR in STAT3-deficient abortion-prone mice. Materials and methodsA STAT3-deficient abortion-prone mouse model was developed using intraperitoneal injection of stattic from embryo day (ED) 5.5 to ED9.5 among pregnant females (C57BL/6). We separately administered BAR1 (5.7 g/kg), BAR2 (11.4 g/kg), progesterone (P4), or distilled water at 10 ml/kg/day from ED0.5 until ED10.5. The embryo resorption rate and placenta-uterus structure were observed on ED10.5. The systemic immune status was examined by analyzing the frequency of immunosuppressive myeloid-derived suppressor cells (MDSCs), the ratio of two macrophage (M) subtypes, and the protein expression of associated molecules. Morphological observation, immunohistochemistry, and western blotting were used to evaluate the vascularization conditions at the maternal-fetal interface. ResultsBAR1, BAR2, or P4 treatment exerted remarkable effects in alleviating embryo resorption rate and disordered placental-uterus structure in STAT3-deficient abortion-prone mice. Western blotting indicated the deficiency of phosphorylated STAT3 and two prime target molecules, PR and HIF-1α, at the maternal-fetal interface under STAT3 inhibition. Simultaneously, BAR2 treatment significantly upregulated their expression levels. The systemic immune environment was disrupted, indicated by the reduced serum cytokine concentrations, MDSCs frequency, M2/M1 ratio, and the expression of immunomodulatory factors. Nonetheless, BAR2 or P4 treatment revived the immune tolerance for semi-allogenic embryos by enhancing the immune cells and factors. Besides, the western blot and immunohistochemistry results revealed that BAR2 or P4 treatment upregulated VEGFA/FGF2 and activated ERK/AKT phosphorylation. Therefore, BAR2 or P4 facilitated vascularization at the maternal-fetal interface in STAT3-deficient abortion-prone mice. ConclusionsBAR sustained pregnancy by reviving the systemic immune environment and promoting angiogenesis at the maternal-fetal interface in STAT3-deficient abortion-prone mice.