bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ikaros regulates basophil and mast cell development and function (P4476)
Authors: Smuda Craig , Rao Kavitha , Brown Melissa 
Published: January 2023

Abstract
Mast cells and basophils are phenotypically similar but functionally distinct myeloid cells, originating from both common and distinct progenitors. Several transcription factors have been identified as important to development of these cells, but regulation of this process remains poorly understood. We have found Ikaros, a diversely spliced DNA-binding protein, to be critical to lineage selection in these cells. Ikaros-/- mice exhibit basophilia in peripheral blood and hematopoietic tissues and expansion of basophil progenitors. Mast cells and their precursors are absent in gut, though there are normal numbers in skin. This phenotype is reflected ex vivo in IL-3 driven bone marrow cultures: in Ikaros-/- cultures, basophils expand substantially and persist longer than in wild-type cultures, while mast cells exhibit an abnormal molecular and functional phenotype, losing expression of mRNA encoding adhesion molecules while inappropriately expressing basophil-associated transcripts and altering surface coactivation molecule expression. Ikaros acts in part by altering histone methylation at the Cebpa and Hes1 loci, genes associated with differential mast cell/basophil development. Restriction of Cebpa expression directly by Ikaros and by Hes1 inhibits basophil development. Ikaros thus restrains basophil development while promoting mast cell differentiation, and tuning of its activity may allow for selectivity between these lineages.
Type I IFN drives emergency myelopoiesis during chronic and acute TLR7 signaling and acute viral infection (P4478)
Authors: Hamerman Jessica , Buechler Matthew , Campbell Daniel , Teal Thomas , Elkon Keith 
Published: January 2023

Abstract
Mice overexpressing TLR7 (TLR7.1 mice) are a model of systemic lupus erythematosus pathogenesis and exhibit peripheral myeloid expansion. We show that TLR7.1 mice have a dramatic expansion of splenic cells that derive from granulocyte/macrophage progenitors (GMP) compared with wild-type mice. In the bone marrow, TLR7.1 mice exhibited hallmarks of emergency myelopoiesis and contained a discrete population of Sca-1+ GMP, termed emergency GMP (eGMP). The emergency myelopoiesis and peripheral myeloid expansion in TLR7.1 mice was dependent on type I IFN signaling. eGMP were found in a type I IFN-dependent manner during both acute and chronic TLR7 agonist administration and during acute LCMV infection. Using in vitro colony forming unit assays, we found that eGMP are superior myeloid precursors than GMP. In vivo, eGMP turnover more than GMP, suggesting that the superiority of eGMP to generate myeloid cells in vitro may stem from their increased ability to proliferate. This study shows that type I IFN can act upon myeloid progenitors to promote the development of emergency GMP, which leads to an expansion of their progeny in the periphery. Further studies are underway to understand the molecular mechanisms that differentiate eGMP from GMP and other myeloid progenitor cells.
Dendritic cell differentiation mediated by IRF4 and IRF8 requires PKCβII (P4480)
Authors: Spangler Haley , Farren Matt , Carlson Louise , Abrams Scott , Lee Kelvin 
Published: January 2023

Abstract
To better understand how Dendritic Cell (DC) subsets are differentiating, we investigated two essential arms of DC differentiation and how they interact to mediate this process. The transcription factors Interferon Regulatory Factor 4 and 8 (IRF4 and IRF8) are critical for DC differentiation, but have varying roles depending on the stimuli. While IRF8 is required for FLT3-L induced plasmacytoid DC differentiation, and IRF4 is required for GM-CSF induced conventional DC differentiation, it is not well characterized how these two molecules are differentially regulated. We found that Protein Kinase C βII (PKCβII) is activated by both FLT3-L and GM-CSF, and that it is required for DC differentiation when either of these stimuli is used to generate DCs from progenitor cells. Since PKCβII and these IRFs are contributing to DC differentiation we hypothesized they were interacting. We discovered that PKCβII upregulates IRF8 when activated by FLT3-L or phorbol ester (PMA, a known activator of PKCβII), and IRF8 upregulation is lost with the addition of a PKCβII inhibitor. Likewise, IRF4 upregulation is induced by PKCβII in cells treated with GM-CSF or PMA, and lost in the presence of a PKCβII inhibitor. We have also found that in IRF8 knockout DCs there are higer levels of PKCβII, suggesting a feedback mechanism by which these IRFs can be autoregulated. Thus, PKCβII regulating these IRFs may be the key to understanding and manipulating DC differentiation.
A type I IFN/Flt3 ligand axis augments plasmacytoid dendritic cell development from common lymphoid progenitors (P4484)
Authors: Lee Chien-Kuo , Chen Yi-Ling , Chen Ting-Ting 
Published: January 2023

Abstract
During infections and inflammation, plasmacytoid dendritic cells (pDCs) are the most potent type I interferon (IFN-I) producing cells. However, the developmental origin of pDCs and the signals dictating pDC generation remain incompletely understood. Here, we report a synergistic role for IFN-I and Flt3 ligand (FL) in pDC development from common lymphoid progenitors (CLPs). Both conventional DCs and pDCs were generated from CLPs in response to FL, while pDC generation required higher concentrations of FL and concurrent IFN-I signaling. An absence of IFN-I receptor, impairment of IFN-I signaling, or neutralization of IFN-I significantly impeded pDC development from CLPs. Furthermore, FL induced IFN-I in CLPs, resulting in Flt3 upregulation that promotes survival and proliferation of CLPs, as well as their differentiation into pDCs. Collectively, these results define a critical role for the FL/IFN-I/Flt3 axis in pDC differentiation from CLPs and identify a potential target for therapeutic intervention in inflammatory and autoimmune diseases associated with pDCs.
Unique role of Cbfβ2 variant in Langerhans cell development (P4492)
Authors: Tenno Mari , Naoe Yoshinori , Muroi Sawako , Taniuchi Ichiro 
Published: January 2023

Abstract
In mammals, Cbfβ protein, known as an essential subunit of Runx transcription factor complexes, are present as two RNA splicing variants, Cbfβ1 and Cbfβ2. To address in vivo roles of individual variant, we have generated mutant mouse strain lacking either Cbfβ1 or Cbfβ2. Here we show that a loss of Cbfβ2 variant results in a defect in Langerhans cell development. In the ear epidermis of adult Cbfβ2-deficient mice, no mature Langerhans cells expressing Langerin and EpCAM were detected. Instead, there were a few larger cells with characteristics of immature Langerhans precursors, such as the dendritic morphology and the expression of MHC class II and CX3CR1. Analysis of bone marrow chimera showed that these Langerin−EpCAM−classII+ cells were radio-resistant residential cells that could not be replaced by donor cells. Analyses of ontogeny of Langerhans cell development around neonatal stage revealed that seeding of CD45+ early progenitor cell to the skin occurred normally in Cbfβ2-deficient mice. However, the next transition into Langerin+EpCAM+ stage, which is know to require for TGFβ signals around day 3 after birth, was severely impaired in the absence of Cbfβ2. Interestingly, although immature Langerhans precursors disappear in adult epidermis by lack of TGFβR1 signals, our results indicate that those cells are stably maintained in the Cbfβ2-deficient mice, suggesting an unique role of Runx3/Cbfβ2 complexes in regulating Langerhans cell development.
TGFβ-signaling in T cells suppresses Tbet mediated CD4+ anti-tumor immune responses in a murine model of lung carcinoma (P2021)
Authors: Andreev Katerina , Soó-Becker Kinga , Engelhardt Marina , Koslowski Michael , Finotto Susetta 
Published: January 2023

Abstract
TGFβ is an important immunosuppression inducing factor in the lung tumor microenvironment and is suggested to facilitate the escape of tumor cells from immunosurveillance. In this project we investigate TGFβ-mediated effects on tumor infiltrating CD4+ T cells, also addressing the question of how TGFβ-induced T cell subtypes, such as Treg and Th17 cells, contribute to tumor cell tolerance. We found an upregulation of TGFβ in patients affected by lung carcinoma. In a murine model of lung carcinoma we also observed a significant reduction of tumor growth as well as prolonged survival of CD2TβRIIdN mice, which exhibit a defective TGFβ-signaling in T cells. This was accompanied by increased numbers of tumor infiltrating effector T cells, reduced induction of Tregs in the tumor tissue and enhanced Th1 cell responses. Similarly, reduced tumor load was observed after intranasal application of anti-TGFβ1 antibodies to tumor bearing wild-type mice. By contrast, Tbet -/- mice showed increased tumor growth. To further analyze the opposing effects of Tbet and TGFβ on CD4+ anti-tumor responses, we crossed CD2TβRIIdN and Tbet -/- mice and found that this newly generated mouse strain was not protected from tumor development. Moreover the results suggest a relation between tumor growth and Th17 cell responses in this context. Together, our data reinforce the importance of Tbet for anti-tumor immune responses and outline the manifold role of TGFβ for lung cancer.
CD28:a pro-survival signaling molecule in multiple myeloma as a novel therapeutic target (P2029)
Authors: Murray Megan , Nair Jayakumar , Lee Kelvin 
Published: January 2023

Abstract
Multiple myeloma (MM) survival is dependent on the bone marrow microenvironment and is mediated by the receptor CD28, expressed on MM cells. CD28 expression correlates clinically with poor outcomes, and we have shown that CD28 signaling protects MM from chemotherapy. However, the molecular pathway by which CD28 does this is not clear. Since CD28 signals via a PI3K-Akt-FoxO3a axis in T cells, we interrogated whether this pathway is critical in MM. We observed that blockade of PI3K or Akt abrogates CD28-mediated survival. Upon CD28 activation, transcription factor FoxO3a is phosphorylated and excluded from the nucleus. Being downstream of FoxO3a, we examined whether the pro-apoptotic molecule Bim is regulated by CD28. Indeed, CD28 activation downregulates Bim, blockade upregulates it, and Bim silencing abrogates sensitivity to CD28 blockade. To confirm that stromal cells protect MM, we cocultured MM and dendritic cells and observed increased survival. However, if CD28 or CD80/86 is blocked, protection is completely abrogated. To examine if this is relevant in vivo, we used the murine myeloma model Vk*MYC and a SCID/human model. In either case, treatment with CTLA4-Ig (to block CD80/86) in combination with a sub-therapeutic chemotherapy dose was able to significantly decrease tumor burden and extend survival. Taken together, these data suggest that CD28 is a direct mediator of chemotherapy resistance in vivo, and blockade of CD28 represents a novel target for clinical therapy.
Inhibition of the Heat Shock Protein receptor CD91 abrogates concomitant anti-tumor immunity (P2035)
Authors: Zhou Yu , Binder Robert 
Published: January 2023

Abstract
Immunosurveillance mechanisms of tumors depend on the host’s ability to efficiently cross-present tumor antigens. We provide evidence here that heat shock proteins (HSPs), when released into the tumor microenvironment, is the antigen carrier necessary for priming concomitant tumor specific immunity. These responses require CD91- the endocytic and signaling receptor for the immunogenic HSPs. In our study, we generated CD11c-specific CD91 knockout mice and showed that tumors grew faster in those mice, compared to CD91+/+ mice. In addition, we abrogated the interaction of tumor-derived HSP with CD91 in vivo by over-expression of Receptor Associated Protein (RAP), an endogenous CD91 antagonist. The data showed that: first, tumors expressing RAP grew with significantly faster kinetics than the non-RAP expressing counterparts in wild type mice, although this difference was non-existent in immunocompromised mice; second, RAP-expressing tumors, when used as an immunogen in tumor prophylaxis, were significantly less efficient in priming immune responses; third, in the presence of RAP, less amount of tumor-derived EGFP-labeled HSPs were taken up by APCs in draining lymph nodes. In summary, our study demonstrates that the HSP-CD91 pathway is critical for establishment of concomitant immunity. Considering that elevated RAP levels have been reported in cancer patients, we propose a novel mechanism of immune evasion for tumors expressing competing ligands for immune receptors such as CD91.
Tumor microenvironment induces selective migration of specific subsets of natural killer cells and inhibits their cytolytic function. (P2039)
Authors: Lal Girdhari , Paul Sourav , Singh Amit 
Published: January 2023

Abstract
Cytolytic function of NK cells plays an important role to regulate the cancer growth. We hypothesized that inflamed tumor microenvironment regulates the migration of specific subset of NK cells and inhibits their cytolytic function. To investigate the affect of tumor microenvironment on NK cell migration and function, B16F10 melanoma cells (1 X 106 cells/mouse) were injected (s.c.) into C57BL/6 mice. Depletion of NK cells showed 3-4 fold increased tumor growth compared to control IgG treated mice. Tumor transplanted (day 10) and naïve mice did not showed any significant difference in percentage and absolute number of CD11b+CD27+, CD11b+CD27- or CD11b-CD27+ NK cells in spleen and lymph nodes. However, CD11b+CD27+CD3-NK1.1+ cells were selectively recruited into the tumor. At day 5, increase CD31+ endothelial cell staining were observed. qRT-PCR analysis of tumor associated endothelial cells (CD31+CD45- cells) showed increased CCL2, CCL21, CXCL10, and CXCL12 mRNA expression compared to splenic blood endothelial cells. Tumor infiltrating NK cells (day 13) showed increased expression of CCR2, CXCR4, IL-6, FasL mRNA expression, and decreased perforin, IFNg and IL-21 expression compared to splenic NK subsets. These results demonstrate that inflamed tumor microenvironment selectively recruits a specific subset of NK cell and inhibit their cytolytic function. This suggests that modulating tumor microenvironment may be key to boost the NK cell function to control cancer progression.
Endotoxin tolerance in circulating monocytes of Chronic Lymphocytic Leukemia: a cross-tolerance mechanism (P2061)
Authors: Lopez-Collazo Eduardo , Jurado Teresa , Siliceo María , Cordoba Raul , Hernandez-Jimenez Enrique , Toledano Victor 
Published: January 2023

Abstract
Monocyte exposure to tumor cells induces a transient state in these cells rendering them refractory to further cancer exposure. This phenomenon, termed "tumor tolerance", is characterized by a reduction of pro-inflammatory cytokines production in response to tumors. In addition, exposure to consecutive endotoxin stimuli induces a similar refractory state called “endotoxin tolerance”. In the past, we found that these two phenomenons comprise IRAK-M up regulation and a marked down-regulation of MHCII molecules as well as of the MHCII master regulator, CIITA. These cells combine an impaired capability for antigen presentation with potent phagocytic activity and exhibit an M2-like phenotype. Herein we have demonstrated that after a first exposition to MEC1 (a CLL cell line), human monocytes failed to mount an inflammatory response against bacterial endotoxin, thus they showed a cross tolerance in vitro. We also tested the implication of miRNAs in this process. We confirmed our data in circulating cells isolated from Chronic Lymphocytic Leukemia suggest an explanation for the high frequency of infections in these kinds of patients.
Mast cell derived histamine promotes the activity of monocytic myeloid derived suppressor cells (P2065)
Authors: Saleem Sheinei , Martin Rebecca , Bear Harry , Conrad Daniel 
Published: January 2023

Abstract
Until recently, the interaction between mast cells (MCs) and CD11b+Gr-1+ myeloid derived suppressor cells (MDSCs) was limited to recruitment of MDSCs to the tumor site. However, we report that MCs are also needed for the activity of MDSCs. MDSCs failed to promote B16 melanoma metastasis in MC deficient mice. This was dependent on monocytic Ly6C+ MDSCs while granulocytic Ly6G+ had no effect. In vitro studies showed increased Th2 cytokine production by both cells. Given these observations and literature indicating histamine as a promoter of tumor expansion, myeloid cell proliferation, and Th2 skewed immunity; we investigated histamine in the MC/MDSC interaction. MDSCs were shown to express histamine receptor 1 (HR1). Furthermore, histamine enhanced MDSC survival and preferentially expanded monocytic LY6C+ MDSCs. This was abrogated with HR1 antagonization. Additionally, histamine upregulated Arg1 and iNOS enzyme expression, both of which are utilized by MDSCs to inhibit T cell activity. This was further supported by the finding that in the presence of MCs, MDSCs were more effective at inhibiting T cell proliferation. Taken together, our data indicates that beyond recruitment, MCs regulate MDSC activity at the tumor site via histamine release. These findings have important implications for the use of anti-histamines in cancer patients being simultaneously treated for allergies. Oncologists should consider this new MC/MDSC interaction when determining therapeutic interventions.
Opposing effects of myeloid vs. lymphoid deletion of adenosine A2A receptors on anti-tumor immune responses (P2007)
Authors: Cekic Caglar , Linden Joel 
Published: January 2023

Abstract
Extracellular adenosine is generated as part of immune escape programming orchestrated by tumor cells and regulatory cells. Adenosine A2A receptors (A2AR) on innate and adaptive immune cells are high affinity targets for adenosine-mediated immune suppression. In this study we demonstrate that myeloid-deletion of adenosine A2A receptor gene (adora2a) strongly inhibit tumor growth and metastasis. This was associated with increased APC function of macrophages and increased the numbers and activation of cytotoxic lymphocytes. Surprisingly, lymphoid deletion of adora2a markedly increased tumor growth and decreased the numbers of effector/memory T cells in the tumor. Mechanistic studies revealed that adora2a deletion in T cells severely impacts generation of the long/lived memory/effector T cell population within the tumor consistent with recent studies indicating that A2AR activation reduces activation-induced cell death. The results of this study have important implications for the development cell-based therapies targeting adenosine receptors.
Systemic lymphopenia results in loss of suppressive lymphocytes from precancerous skin (P2081)
Authors: Leggatt Graham , Mattarollo Stephen , Yong Michelle , Nissen Michael , Frazer Ian 
Published: January 2023

Abstract
We have previously demonstrated an immunosuppressive role for NKT cells that infiltrate hyperplastic skin epithelium in transgenic mice expressing HPV16E7 oncoprotein under a keratin 14 promoter (K14E7 mice)(Mattarollo et al.(2010) J. Immunol. 184:1242-1250). However, depletion of NKT cells is not easily achieved in either mouse or human. We hypothesized that systemic depletion of lymphocytes might result in turnover of NKT cells (and other lymphocytes) within the precancerous skin without replacement from the circulation. Without these locally suppressive populations, the precancer might then be more susceptible to a transferred immune system. When K14E7 skin was grafted onto RAG1-/- mice, which lack lymphocytes, the grafted skin became depleted of T cells (including NKT cells) within 7 days and remained depleted. Depletion of skin lymphocytes could also be achieved using cyclophosphamide and fludarabine, although with less efficiency. Preliminary data suggests that K14E7 skin grafts on RAG1-/- mice become susceptible to graft rejection after transfer of a new immune system. Together the data suggest that systemic lymphodepletion results in a loss of local, suppressive lymphocytes at the precancerous site and that this might enhance the immune mediated clearance of skin precancers.
The role of paracrine IL-6 in plasma cell neoplasia development (P2083)
Authors: Rosean Timothy , Tompkins Van , Waldschmidt Thomas , Janz Siegfried 
Published: January 2023

Abstract
Plasma Cell Neoplasms (PCN), such as multiple myeloma, are cancers of terminally differentiated B cells, and are the second most common blood cancers overall. PCN remains incurable, and therefore research into the development of disease is increasingly necessary. IL-6, a pro-inflammatory cytokine, has emerged as a key driver in PCN development, in part through its collaboration with the proto-oncogene c-Myc. Mice containing a gene insertion of c-Myc into the IgH locus (iMyc) and overexpressing human IL-6 (hIL-6) develop PCN at a significantly increased rate and incidence. While IL-6 is important for PCN development, it is unknown which source of IL-6, pre-malignant cells or the microenvironment, is more important. To examine this question, we developed an adoptive transfer system to investigate tumor development. Specifically, when premalignant B cells from iMyc mice are transferred into syngeneic recipients, PCN develops around 120 days post-transfer. To test whether the source of IL-6 affects PCN development, we performed two experiments monitoring tumor development. First, iMyc or iMyc/IL-6-/- premalignant B cells were transferred into syngeneic recipients. There was no significant difference in tumor onset. Secondly, iMyc/hIL-6 premalignant B cells were transferred into BALB/c or C.IL-6-/- recipients. Tumor onset was significantly delayed in C.IL-6-/- recipients, demonstrating for the first time the importance of paracrine IL-6 in PCN development.
Liver natural killer T cells enhance, rather than inhibit, liver metastases arising from intraocular melanomas in mice. (P2087)
Authors: Sadegh Leila , Chen Peter , Niederkorn Jerry 
Published: January 2023

Abstract
Uveal melanoma (UM) is the most common intraocular tumor in adults and liver metastasis is the leading cause of death in UM patients. We have shown that NKT cell-deficient mice develop significantly less liver metastasis from intraocular melanomas than wild-type (WT) mice. Here we examine the interplay between liver NKT cells and NK cells in resistance to liver metastases from intraocular melanomas. NKT cell-deficient CD1d-/- mice and WT C57BL/6 mice treated with anti-CD1d antibody developed significantly fewer liver metastases than WT mice following either intraocular or intrasplenic injection of B16LS9 melanoma cells. Increased metastases in WT mice was associated with reduced liver NK cytotoxicity. However, liver NK cytotoxic activity was identical in non-tumor-bearing NKT cell-deficient mice and WT mice, indicating that liver metastases were crucial for suppression of liver NK cells. Depressed liver NK cytotoxicity in WT mice was associated with increased IL-10 production by bone marrow-derived liver cells and increased IL-10 receptor expression on liver NK cells. IL-10-/- mice had significantly fewer liver metastases than WT mice, but were not significantly different from NKT cell-deficient mice. Thus, development of melanoma liver metastases is associated with upregulation of IL-10 in the liver and an elevated expression of IL-10 receptor on liver NK cells. Impaired liver NK activity is NKT cell-dependent and only occurs in hosts with melanoma liver metastases.