Transgenic Bone Marrow Research Articles

Multistep IgE Mast Cell Desensitization Is a Dose- and Time-Dependent Process Partially Regulated by SHIP-1

Multistep mast cell desensitization blocks the release of mediators following IgE crosslinking with increasing doses of Ag. Although its invivo application has led to the safe reintroduction of drugs and foods in IgE-sensitized patients at risk for anaphylaxis, the mechanisms of the inhibitory process have remained elusive. We sought to investigate the kinetics, membrane, and cytoskeletal changes and to identify molecular targets. IgE-sensitized wild-type murine (WT) and FcεRIα humanized (h) bone marrow mast cells were activated and desensitized with DNP, nitrophenyl, dust mites, and peanut Ags. The movements of membrane receptors, FcεRI/IgE/Ag, actin, and tubulin and the phosphorylation of Syk, Lyn, P38-MAPK, and SHIP-1 were assessed. Silencing SHIP-1 protein was used to dissect the SHIP-1 role. Multistep IgE desensitization of WT and transgenic human bone marrow mast cells blocked the release of β-hexosaminidase in an Ag-specific fashion and prevented actin and tubulin movements. Desensitization was regulated by the initial Ag dose, number of doses, and time between doses. FcεRI, IgE, Ags, and surface receptors were not internalized during desensitization. Phosphorylation of Syk, Lyn, p38 MAPK, and SHIP-1 increased in a dose-response manner during activation; in contrast, only SHIP-1 phosphorylation increased in early desensitization. SHIP-1 phosphatase function had no impact on desensitization, but silencing SHIP-1 increased β-hexoxaminidase release, preventing desensitization. Multistep IgE mast cell desensitization is a dose- and time-regulated process that blocks β-hexosaminidase, impacting membrane and cytoskeletal movements. Signal transduction is uncoupled, favoring early phosphorylation of SHIP-1. Silencing SHIP-1 impairs desensitization without implicating its phosphatase function.

Dominant-Negative VPS4A Mutations Causing Congenital Dyserythropoietic Anemia Disrupt Iron Trafficking of Terminal Erythropoiesis

We recently reported on a syndrome in humans caused by VPS4A mutations characterized by dyserythropoiesis, hemolytic anemia, and neurodevelopmental delay. VPS4A is an ATPase that participates with the Endosomal Sorting Complex Required for Transport (ESCRT)-III complex in a variety of cellular processes including the abscission step of cytokinesis and endo-lysosomal trafficking. De novo dominant-negative mutations in the ATPase domain of VPS4A are associated with erythroblast cytokinesis failure and altered trafficking of the transferrin receptor (TfR1/CD71) consistent with known roles for ESCRT-III in cell division and endosomal transport. However, the mechanisms by which ESCRT-III dysfunction impairs erythropoiesis remain unclear. In addition to erythroid dysplasia in the bone marrow, patients with dominant-negative VPS4A mutations have hypochromic reticulocytes exhibiting high levels of TfR1 expression and mature RBCs which aberrantly retained TfR1 on the membrane. We further evaluated the reticulocytes from two patients with heterozygous VPS4A G203E mutations, one of the two previously described dominant-negative mutations causing this syndrome. In labeled-transferrin uptake assays, patient reticulocytes endocytosed less transferrin than control reticulocytes despite having increased TfR1 on their surface. RNA-sequencing analysis of CD71+ reticulocytes from patients and normal controls revealed dysregulated expression of genes involved in iron transport and homeostasis including upregulation of STEAP3 metalloreductase and Divalent Metal Transporter 1, DMT1 (SLC11A2), involved in export of iron from the endosome to the cytoplasm (4.4-fold, p<0.01 and 8.4-fold, p<0.001, respectively) (Figure 1A). As expected, expression of TFRC, encoding TfR1/CD71, was markedly increased (22-fold, p<0.001). By electron microscopy (EM), we observed evidence of iron overload within patient erythroblasts in the form of electron dense ferritin granules (Figure 1B); EM images also revealed irregular endolysosomal compartments. Adult mice with erythroid-specific expression of a dominant-negative VPS4 mutant (EporCre-Vps4bE235Q) develop anemia. Vps4bE235Q transgenic bone marrow phenocopies human disease containing binucleated erythroblasts and cytoplasmic bridges connecting erythroblasts, indicating this mouse model could be used to further investigate the pathogenic mechanisms of VPS4 mutations on erythropoiesis. Taken together, our studies on human and murine erythropoiesis provide the first evidence that dominant-negative VPS4A mutations, causing erythroblast cytokinesis failure and binucleated erythroblasts, also disrupt iron uptake and trafficking through the endo-lysosomal pathway of terminal erythropoietic cells. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

CHRFAM7A expression in mice increases resiliency after injury.

The CHRNA7 gene encodes the α-7 nicotinic acetylcholine receptor (α7nAchR) that regulates anti-inflammatory responses to injury; however, only humans express a variant gene called CHRFAM7A that alters the function of α7nAChR; CHRFAM7A expression predominates in bone marrow and monocytes/macrophages where the CHRFAM7A/CHRNA7 ratio is highly variable between individuals. We have previously shown in transgenic mice that CHRFAM7A increased emergency myelopoiesis from the bone marrow and monocyte/macrophage expression in lungs. CHRFAM7A transgenic mice are compared to age- and gender-matched wild-type (WT) siblings. We utilized a model of sepsis using LPS injection to measure survival. Lung vascular permeability was measured after severe burn injury in WT vs. CHRFAM7A transgenic mice. Bone marrow CHRFAM7A expression was evaluated using adoptive transfer of CHRFAM7A transgenic bone marrow into WT mice. Here, we demonstrate that CHRFAM7A expression results in an anti-inflammatory phenotype with an improved survival to LPS and decreased acute lung injury in a severe cutaneous burn model compared to WT. These data suggest that the relative expression of CHRFAM7A may alter resiliency to injury and contribute to individual variability in the human systemic inflammatory response (SIRS) to injury.

Overexpression of Human TLR8 Causes Fatal Anemia in SLE-Prone Mice By Altering the Bone Marrow Erythropoietic Niche

Anemia is a common hematologic abnormality in patients with active systemic lupus erythematosus (SLE), a disease characterized by innate immune system activation by nucleic acid containing immune complexes and cell debris. Work in mouse models has shown that overactivation of several cytoplasmic innate immune sensors by either self-DNA or self-RNA specifically leads to erythroid cell death in the fetal liver while sparing other hematopoietic cell lineages.The endosomal receptors TLR7 and TLR8 both recognize ssRNA in humans. TLR7 overexpression in mice causes a lupus syndrome that includes the development of mild to moderate anemia (Hb >10) and thrombocytopenia and is associated with spleen histiocytosis, autoimmune hemolysis, erythrophagocytosis and compensatory stress erythropoiesis in the spleen. A recent study demonstrated that patients with TLR8 gain of function mutations present with immunodeficiency, inflammation and bone marrow failure. However the role of TLR8 in SLE has been difficult to study in mice because it has a 5 amino acid deletion that attenuates its RNA binding capacity.To address the role of TLR8 in SLE, we overexpressed human TLR8 in a lupus mouse model (huTLR8tg.Sle1.Yaa) using a BAC transgene. 50% of homozygous huTLR8tg.Sle1.Yaa mice developed severe anemia (Hb<9) resulting in early mortality starting at 3-4.5 months of age. This phenotype required both the Sle1 and Yaa loci that promote the formation of high titer anti-chromatin and anti-RNA antibodies and onset of nephritis at >6 months of age. There was no difference in autoantibody titers between Sle1.Yaa wt and huTLR8tg mice and early death was not due to premature onset of renal disease. All mice had normal RBC indices prior to 10 weeks of age. Anemia was associated with an increase in bone marrow (BM) trabecular bone and a decrease in erythroblastic islands (EBI) in the BM with compensatory stress erythropoiesis leading to reticulocytosis and vast splenomegaly. RBC half-life was normal even after the development of reticulocytosis, but decreased in severely anemic mice as a pre-terminal event. Using CFSE labeling of RBCs we showed that hemophagocytosis occurred in vivo as a result of expansion of phagocytic red pulp macrophages.Flow cytometry of BMs from transgenic mice showed normal erythroid progenitors but a block at the late CFU-E/early proerythroblast stage leading to overall decreased terminal erythroid differentiation. Single cell RNAseq of EBIs isolated from transgenic BMs confirmed the block in erythropoiesis. The erythroblast cluster proximal to the block had a signature of mitochondrial stress and decreased proliferation. Spleen EBIs from transgenic mice were characterized by a low frequency of early erythroblasts compared with BM EBIs. We found 6 related clusters of EBI central macrophages in the BMs of both wt and transgenic mice. In transgenic mice, most of these displayed an inflammatory and Type 1 IFN signature. One cluster (M2) expressed all the classical central macrophage phenotypic markers in wt mice but was characterized in transgenic mice by downregulation of multiple phagocytic receptors and a 5-fold decrease of VCAM1 expression. Loss of VCAM1 and downregulation of CD169 in central macrophages of transgenic BMs was confirmed by flow cytometry. By contrast spleen central macrophages from transgenic mice retained VCAM and CD169 expression.Together, these results suggest that failure of BM erythropoiesis in huTLR8 transgenic SLE.Yaa lupus-prone mice, in which the acquisition of anti-nucleic acid autoantibodies drives excess innate stimulus through TLR7 and huTLR8, is due to a block in differentiation from CFU-E to the early proerythroblast stage; this is associated with an inflammatory phenotype specifically in BM erythroblastic island central macrophages and down regulation of adhesion and phagocytic receptors. Stress erythropoiesis in the spleens is associated with vast expansion of red pulp macrophages with phagocytic properties and fatal anemia is associated with a decrease in red blood cell half-life, suggesting that excessive RBC phagocytosis, coupled with insufficient erythroblast progenitors, eventually exceeds the capability of stress erythropoiesis to replace the RBC mass. DisclosuresKalfa: Agios Pharmaceuticals, Inc.: Other: Steering Committee, Research Funding; FORMA Therapeutics, Inc: Research Funding. Paulson: Forma Therapeutics: Consultancy. Blanc: Keros Therapeutics, Inc.: Consultancy.

Clearance of skin-homing CCR7+ neutrophils by conventional type1 dendritic cells regulates cutaneous local autoimmunity and infection

Abstract A rapid neutrophil response is essential for immunity against infections, however impaired elimination or migration can inflict significant tissue damage by exacerbated inflammation. Here we show that neutrophils recruited to inflamed or infected skin are rapidly redirected to skin-draining lymph nodes (dLNs) and non-draining secondary lymphoid tissues. Using transgenic mouse models and bone marrow chimeras, cutaneous inflammation is induced with imiquimod, a TLR7-mediated psoriasis-like model, or skin infection is induced by Staphylococcus aureus. We show that neutrophils migrate to the dLNs through lymphatic vessels in a CC-motif chemokine receptor 7 (CCR7)-dependent manner and are phagocytosed by resident conventional type1 dendritic cells in the dLNs when entering the lymph node, a mechanism contributing to neutrophil clearance. Deficiency of CCR7 impairs neutrophil elimination in the dLNs and leads to neutrophilic accumulation in the skin, which in turn leads to an exacerbated phenotype in a model of psoriasis-like local inflammation as well as improved clearance and immunity against cutaneous Staphylococcus aureus infection. Overall, our findings explain how impaired neutrophil migration and clearance in the dLNs could regulate cutaneous autoimmunity and infection.

Impact of age-associated decreases in thymic B cell expression of Aire and self-antigen genes on T cell tolerance

Abstract Susceptibility to many autoimmune diseases increases with age, but the mechanisms linking aging and autoimmunity remain incompletely understood. One hallmark of the aging immune system is atrophy of the thymus, the primary site of T lymphocyte generation and tolerance induction. Aging is also associated with declines in critical thymic functions, including expression of tissue restricted self-antigen (TRA) genes important in tolerance induction. We have focused on a subset of TRAs transcribed preferentially by thymic B cells under control of the Autoimmune regulator (Aire). This expression results in clonal deletion (tolerization) of T cells specific for these antigens which are typically expressed in peripheral tissues. Recently, we found that expression of both Aire and Aire-dependent TRA genes in thymic B cells declines with aging in both mice and humans, leading to the prediction that central T cell tolerance to B cell TRAs would be diminished in older individuals. As a direct test of this hypothesis, splenic B cells from young and aged AdBDC transgenic mice (present an Aire-regulated BDC2.5 antigen) were transferred into irradiated hosts reconstituted with BDC2.5 TCR transgenic bone marrow. We find that aging diminishes the capacity of AdBDC B cells to mediate clonal deletion of cognate BDC2.5 T cells. We also used MHCII tetramers and ELISpot to detect T cells recognizing a model TRA expressed in thymic B cells, Titin (Ttn), an auto-antigen involved in late-onset myasthenia gravis, in the thymus and secondary lymphoid organs of young and aged mice. Together, our preliminary results suggest that the reduced capacity of aged thymic B cells to express Aire also impairs their ability to properly tolerize developing T cells in the thymus.

Experimental study on transplantation of microencapsulated transgenic bone marrow mesenchymal stem cells for early steroid-induced osteonecrosis of femoral head in rabbits

To investigate the effect of microencapsulated transgenic bone marrow mesenchymal stem cells (BMSCs) transplantation on early steroid induced osteonecrosis of femoral head (SONFH) in rabbits. Alginate poly- L-lysine-sodium alginate (APA) microencapsulated transgenic BMSCs with high expression of Foxc2 were prepared by high-voltage electrostatic method. Part of the cells were cultured in osteoblasts and observed by alizarin red staining at 2 and 3 weeks. Forty New Zealand white rabbits were used to prepare SONFH models by using hormone and endotoxin. Thirty two rabbits who were successful modeling were screened out by MRI and randomly divided into 4 groups (groups A, B, C and D, n=8); another 6 normal rabbits were taken as normal control (group E). The rabbits in group A did not receive any treatment; and in groups B, C, and D were injected with normal saline, allogeneic BMSCs, and APA microencapsulated transgenic BMSCs respectively after core decompression. At 6 and 12 weeks after operation, specimens of femoral head were taken for HE staining to observe bone ingrowth; the expressions of osteocalcin (OCN), peroxisome proliferative activated receptor γ 2 (PPARγ-2), and vascular endothelial growth factor (VEGF) proteins were observed by immunohistochemistry staining. At 12 weeks after operation, the bone microstructure was observed by transmission electron microscope, and the maximum compressive strength and average elastic modulus of cancellous bone and subchondral bone were measured by biomechanics. After 2 and 3 weeks of induction culture, alizarin red staining showed the formation of calcium nodules, and the number of calcium nodules increased at 3 weeks when compared with 2 weeks. The rabbits in each group survived until the experiment was completed. Compared with groups A, B, and C, the trabeculae of group D were more orderly, the empty bone lacunae were less, there were abundant functional organelles, and obvious osteogenesis was observed, and the necrotic area was completely repaired at 12 weeks. Immunohistochemical staining showed that, at 6 and 12 weeks after operation, the expressions of OCN and VEGF in groups A, B, and C were significantly lower than those in groups D and E, while those in groups B and C were significantly higher than those in group A, and in group E than in group D ( P<0.05). The expression of PPARγ-2 was significantly higher in groups A, B, and C than in groups D and E, and in group A than in groups B and C, and in group D than in group E ( P<0.05). At 12 weeks after operation, biomechanical test showed that the average elastic modulus and maximum compressive strength of cancellous bone and subchondral bone in groups D and E were significantly higher than those in groups A, B, and C ( P<0.05); there was no significant difference between groups A, B, and C and between groups D and E ( P>0.05). In vivo transplantation of microencapsulated transgenic BMSCs can repair early SONFH in rabbits.

Investigation of resident and recruited macrophages following disc injury in mice.

Macrophages, particularly M1 macrophages, produce proinflammatory cytokines and contribute to the degenerative process in injured intervertebral discs (IVDs). We previously showed that macrophages in both intact and injured IVDs increased following IVD injury. Resident macrophages and macrophages recruited from the peripheral blood have distinct roles in tissue. However, it remains to be determined whether increased macrophages derive from resident or recruited macrophages. We investigated the origin of M1 macrophages in injured IVDs using green fluorescent protein (GFP) transgenic bone marrow chimeric mice. The M1 macrophage marker, CD86, increased in both disc-derived resident macrophages and bone marrow-derived macrophages (BMMs) after lipopolysaccharide/interferon γ stimulation in vitro. Following IVD injury, the proportion of cells positive for the CD86 ligand, the F4/80 antigen, and the surface glycoprotein CD11b (CD86+ CD11b+ F4/80+) significantly increased in GFP+ populations at days 3, 7, and 14. In contrast, CD86+ CD11b+ F4/80+ cells in GFP- populations significantly increased on day 3, and thereafter decreased on days 7 and 14. The proportion of CD86+ CD11b+ F4/80+ cells in the GFP+ populations was significantly higher than that in the GFP- populations at days 1, 3, 7, and 14. Monocyte chemoattractant protein-1 expression in disc-derived macrophages, but not in BMMs, increased following interleukin-1β stimulation. Our results suggest M1 macrophages following IVD injury originate from recruited macrophages. Resident macrophages may behave differently in IVD injury. The role of resident macrophages needs to be clarified. Further investigation is needed.

Cotargeting the JAK/STAT signaling pathway and histone deacetylase by ruxolitinib and vorinostat elicits synergistic effects against myeloproliferative neoplasms.

The majority of patients with Philadelphia-negative myeloproliferative neoplasms (MPNs) harbor a gain of function mutation V617F in Janus kinase (JAK) 2. Although JAK2 inhibitors such as ruxolitinib have been shown to be clinically efficacious, the hematological toxicity and eventual drug resistance limit its use as monotherapy. Other gene mutations or dysregulation correlated with the disease phenotype and prognosis have been found to contribute to the complexity and heterogeneity of MPNs, giving rise to an increasing demand for combination therapies. Here, we combine ruxolitinib and the histone deacetylase inhibitor vorinostat as a rational combination strategy for MPNs. We tested the combination of ruxolitinib and vorinostat in cells with the JAK2V617F mutation, such as HEL cells, c-Kit+ cells from JAK2V617F transgenic mice and bone marrow mononuclear cells (BMMNCs) from patients with MPN. Our results showed significant synergistic effects of this combination strategy. Cotreatment with ruxolitinib and vorinostat synergistically induced apoptosis, cell cycle arrest and inhibition of the colony-forming capacity of HEL cells by attenuating the JAK/signal transducer and activator of transcription (STAT) and protein kinase-B (AKT) signaling pathways. In particular, cotreatment with ruxolitinib and vorinostat prevented the formation of large colonies of colony-forming unit-granulocyte/erythroid/macrophage/megakaryocytes (CFU-GEMMs) and colony-forming unit-granulocyte/macrophages (CFU-GMs) derived from the BMMNCs of patients with MPN. Taken together, these data provided preclinical evidence that the combination of ruxolitinib and vorinostat is a potential dual-target therapy for patients with MPN.

Atrophied thymus creates tTreg repertoire holes altering an antigen-specific population in the periphery

Abstract We have shown that there is an increased ratio of total thymic T regulatory (tTreg) cells to thymic T conventional (tTcon) cells generated by the atrophied thymus related to aging. This observation, coupled with the accumulation of peripheral Treg (pTreg) cells with age, poses the difficult question of why Tregs in the periphery of the elderly are unable to suppress amplified self-reactivity-induced inflammaging. We utilized a chimeric mouse model with immune system reconstitution in which lethally irradiated rat insulin promotor-driven (RIP) mOVA host mice received mixed OT-II TCR transgenic and wild-type bone marrow, each expressing distinct congenic identifiers (CD45.1 vs CD45.2). In this system, OVA serves as a mock self-antigen, which is expressed mainly in the pancreas of the host mice. Further, our mOVA host mice carried a FoxN1-floxed gene, for induction of conditional FoxN1 knock-out, resulting in thymic atrophy analogous to age-related thymic atrophy. We observed that chimeric mice with induced thymic atrophy exhibited significantly decreased OVA-specific (OT-II) Tregs, but not total (pan) Tregs, in the spleen and pancreas. The specific Treg cells of mice with thymic atrophy were also more instable, showing relatively decreased FoxP3 expression, and had greater plasticity, showing an increased Th1-like (IFNγ+FoxP3+) Treg phenotype. Overall, our preliminary results suggest that thymic atrophy creates changes in the antigen-specific repertoire during tTreg generation resulting in potential “holes” that may contribute to inflammaging in the elderly and negatively impact Treg cell-mediated regulation in the aged immune system. (Supported by NIH/NIAID 1R01AI121147)

A Novel iRFP-Incorporated in vivo Murine Atherosclerosis Imaging System

By using near-infrared fluorescent protein (iRFP)-expressing hematopoietic cells, we established a novel, quantitative, in vivo, noninvasive atherosclerosis imaging system. This murine atherosclerosis imaging approach targets macrophages expressing iRFP in plaques. Low-density lipoprotein receptor-deficient (LDLR−/−) mice transplanted with beta-actin promoter-derived iRFP transgenic (TG) mouse bone marrow (BM) cells (iRFP → LDLR−/−) were used. Atherosclerosis was induced by a nonfluorescent 1.25% cholesterol diet (HCD). Atherosclerosis was compared among the three differently induced mouse groups. iRFP → LDLR−/− mice fed a normal diet (ND) and LDLR−/− mice transplanted with wild-type (WT) BM cells were used as controls. The in vivo imaging system (IVIS) detected an enhanced iRFP signal in the thoracic aorta of HCD-fed iRFP → LDLR−/− mice, whereas iRFP signals were not observed in the control mice. Time-course imaging showed a gradual increase in the signal area, which was correlated with atherosclerotic plaque progression. Oil red O (ORO) staining of aortas and histological analysis of plaques confirmed that the detected signal was strictly emitted from plaque-positive areas of the aorta. Our new murine atherosclerosis imaging system can noninvasively image atherosclerotic plaques in the aorta and generate longitudinal data, validating the ability of the system to monitor lesion progression.

Durable Macrochimerism (&gt;8 weeks) and Pig-Specific T and B Cell Unresponsiveness Following hCD47+ Transgenic GalTKO Pig Intra-Bone Bone Marrow Transplantation in Baboons

Background Recent data have suggested that low levels of preformed anti-non-Gal natural antibody (nAb) limit xenograft survival. Durable mixed xenogeneic chimerism resulted in tolerance of human T cell-independent B cells that produce xenoantibodies, including anti-non-Gal nAb, in mouse models. However, previous attempts at intravenous (IV) α-1,3-galactocyltransferase knockout (GalTKO) pig bone marrow (BM) transplantation (Tx) into non-human primates have been associated with very short-lived chimerism (<24 hours in most cases). In order to achieve improved engraftment with more persistent chimerism, we have recently developed an intra-bone BM (IBBM) Tx strategy in a pig-to-baboon model. We have reported continuous peripheral blood macrochimerism for up to 13 days (mean 7.7 days; range 3–13) post-IBBM/BM-Tx (n=6) and in three animals, macrochimerism reappeared at days 10, 14 and 21 (Am J Transplant 2015). Recent data has suggested that incompatibility between CD47 and SIRPα causes phagocytosis of porcine cells. In this study, we examined whether the use of BM cells from human CD47 (hCD47) transgenic pigs further improves durable chimerism and assessed anti-pig antibody responses following BM Tx,Methods: Four baboons received GalTKO/human CD47(hCD47)/hCD55 pig BM cells, and one received GalTKO/hCD55 porcine BM cells with a conditioning regimen consisting of whole body irradiation thymic, irradiation, ATG, and Rituximab followed by anti-CD40L antibody and MMF. Approximately 2/3 of BM cells were infused intraosseously and the remainder intravenously. Macrochimerism, anti-pig T cells responses, and anti-pig antibody responses were assessed following IBBM Tx. Results were compared with those from baboons that received GalTKO porcine BM cells without any other gene modification (n=6). Results As shown in the Figure (left panel), all four baboons that received hCD47+/hCD55+ porcine BM using the IBBM Tx method maintained durable macrochimerism for >50 days, and two of the 4 maintained blood levels above 1.6%, even at 8 weeks following IBBMTx (red line in the left panel of Fig). We also confirmed macrochimerism in recipients’ BM. A baboon that received hCD55+ but hCD47-negative porcine BM cells also had a slightly higher % of chimerism than GalTKO alone porcine BM cells in the first 3 weeks, but the duration was similar to GalTKO alone porcine BM cells (Blue line vs black line in the left panel of Fig). All recipients of IBBM Tx lost their anti-pig T cell responses in vitro and showed no development of elicited anti-pig ab. Notably, anti-pig nonGal nAb levels in three of 4 recipients of hCD47+/hCD55+ porcine BM cells declined markedly following IBBM Tx (right panel of Fig). Conclusion To our knowledge, this is the first demonstration of (1) durable macrochimerism beyond 8 weeks and (2) reduction of anti-non Gal nAb levels following hCD47+/hCD55+ GalTKO porcine IBBMTx in preclinical pig-to-non-human primate models. The results suggest that IBBMTx using hCD47+ porcine BM is a potent strategy to induce pig-specific T and B cell tolerance across xenogeneic barriers..NIH P01AI45897.:

Blocking Allergic Reaction through Targeting Surface-Bound IgE with Low-Affinity Anti-IgE Antibodies.

Allergic disorders have now become a major worldwide public health issue, but the effective treatment options remain limited. We report a novel approach to block allergic reactivity by targeting the surface-bound IgE of the allergic effector cells via low-affinity anti-human IgE Abs with dissociation constants in the 10-6 to 10-8 M range. We demonstrated that these low-affinity anti-IgE mAbs bind to the cell surface-bound IgE without triggering anaphylactic degranulation even at high concentration, albeit they would weakly upregulate CD203c expression on basophils. This is in contrast to the high-affinity anti-IgE mAbs that trigger anaphylactic degranulation at low concentration. Instead, the low-affinity anti-IgE mAbs profoundly block human peanut- and cat-allergic IgE-mediated basophil CD63 induction indicative of anaphylactic degranulation; suppress peanut-, cat-, and dansyl-specific IgE-mediated passive cutaneous anaphylaxis; and attenuate dansyl IgE-mediated systemic anaphylaxis in human FcεRIα transgenic mouse model. Mechanistic studies reveal that the ability of allergic reaction blockade by the low-affinity anti-IgE mAbs was correlated with their capacity to downregulate the surface IgE and FcεRI level on human basophils and the human FcεRIα transgenic mouse bone marrow-derived mast cells via driving internalization of the IgE/FcεRI complex. Our studies demonstrate that targeting surface-bound IgE with low-affinity anti-IgE Abs is capable of suppressing allergic reactivity while displaying an excellent safety profile, indicating that use of low-affinity anti-IgE mAbs holds promise as a novel therapeutic approach for IgE-mediated allergic diseases.

T Cells Motility in the Colonic Gvhd Is Influenced By Both Cognate Interaction and Microenvironment

Graft-versus-host disease (GVHD) accounts for substantial morbidity and mortality after allogeneic bone marrow transplantation. Allograft T cells are stimulated by both host and donor-derived antigen presenting cells (APCs). After differentiating into T effector cells, donor T cells migrate to GVHD target organs where they mediate damage directly and indirectly. However, very little is known about the dynamics of T cells in GVHD target tissues and how their behaviors are affected by the local environments, including by tissue-resident APCs. We utilized two-photon intravital microscopy (2PIM) to analyze T cell locations, motility and interactions with APCs. 129S1/SVLmJ (129) (H-2b) hosts were irradiated and reconstituted with C57Bl/6 (B6) (H-2b) CD11-YFP transgenic mice bone marrow together with B6 dsRed (RFP) CD8 cells and cyan fluorescent protein (CFP) CD4 cells. Mice were imaged from days 25-42 post-transplant. We focused on the colon which is strongly targeted in this model and in humans and which previously has been difficult to image by 2PIM. In syngeneic B6 into B6 recipients, donor CD11c+, CD8+ and CD4+ cells populate the colonic mucosa. However, a greater number of cells accumulated in the allogenic as compared to syngeneic recipients. Based on the analysis of 7-8 mice per group, T cells in allogenic mice were less motile. The mean CD8 speeds in syngeneic and allogeneic mice were 3.38 ± 0.07 µm/min and 2.21 ± 0.03 µm/min, respectively. Mean CD4 speeds in syngeneic and allogeneic mice were 3.11 ± 0.08 µm/min and 2.38 ± 0.04 µm/min, respectively. The majority of T cells were stationary, with few entering or leaving the imaged volume. Perfusion was confirmed by i.v. rhodamine-dextran; therefore, stationary behaviors was not due to tissue viability. Using optical clearing we imaged whole-mount colonic tissue from mucosa to serosa. T cells were aggregated in the sub-mucosa and infiltrated crypts and surprisingly also the muscular layer. Ki67+ T cells were found throughout, especially in the submucosa. Given the 2PIM data which show few new T cells entering the imaged volumes, these cells were likely stimulated to divide locally. Preliminary data with EdU pulsing suggest this to be the case. To determine whether T cell stability is microenvironment- or antigen-driven, we injected OT-1 TCR transgenic effectors which do not recognize any antigen in the recipient and imaged the next day. Most colonic OT-1 cells showed the same stationary behavior as nearby donor-derived CD4 and CD8 cells, suggesting that factors in the GVHD colon microenvironment drive T cell stability. Nonetheless there was also an antigen-driven component as injection of an anti-MHCII antibody (but not isotype control Ab) increased CD4+ T cell motility presumably by disrupting TCR:MHCII interaction. These results show the motility of T cells in the GVHD colon is influence by both TCR:MHC cognate interactions and by the microenvironment. That T cells are dividing and may be activated in situ, suggesting GVHD may be maintained locally. Current studies are focusing on what antigen-independent factors affect T cell motility and on defining the roles played by tissue APCs. DisclosuresNo relevant conflicts of interest to declare.

Inhibition of the nuclear export of p65 and IQCG in leukemogenesis by NUP98-IQCG.

NUP98 fuses with approximately 34 different partner genes via translocation in hematological malignancies. Transgenic or retrovirus-mediated bone marrow transplanted mouse models reveal the leukemogenesis of some NUP98-related fusion genes. We previously reported the fusion protein NUP98-IQ motif containing G (IQCG) in a myeloid/T lymphoid bi-phenoleukemia patient with t(3;11) and confirmed its leukemogenic ability. Herein, we demonstrated the association of NUP98-IQCG with CRM1, and found that NUP98-IQCG expression inhibits the CRM1-mediated nuclear export of p65 and enhances the transcriptional activity of nuclear factor-κB. Moreover, IQCG could be entrapped in the nucleus by NUP98-IQCG, and the fusion protein interacts with calmodulin via the IQ motif in a calcium-independent manner. Therefore, the inhibition of nuclear exports of p65 and IQCG might contribute to the leukemogenesis of NUP98-IQCG.

Cis-vaccenic acid induces differentiation and up-regulates gamma globin synthesis in K562, JK1 and transgenic mice erythroid progenitor stem cells

Gamma globin induction remains a promising pharmacological therapeutic treatment mode for sickle cell anemia and beta thalassemia, however Hydroxyurea remains the only FDA approved drug which works via this mechanism. In this regard, we assayed the γ-globin inducing capacity of Cis-vaccenic acid (CVA). CVA induced differentiation of K562, JK1 and transgenic mice primary bone marrow hematopoietic progenitor stem cells. CVA also significantly up-regulated γ-globin gene expression in JK-1 and transgenic mice bone marrow erythroid progenitor stem cells (TMbmEPSCs) but not K562 cells without altering cell viability. Increased γ-globin expression was accompanied by KLF1 suppression in CVA induced JK-1 cells. Erythropoietin induced differentiation of JK-1 cells 24h before CVA induction did not significantly alter CVA induced differentiation and γ-globin expression in JK-1 cells. Inhibition of JK-1 and Transgenic mice bone marrow erythroid progenitor stem cells Fatty acid elongase 5 (Elovl5) and Δ(9) desaturase suppressed the γ-globin inductive effects of CVA. CVA treatment failed to rescue γ-globin expression in Elovl5 and Δ(9)-desaturase inhibited cells 48 h post inhibition in JK-1 cells. The data suggests that CVA directly modulates differentiation of JK-1 and TMbmEPSCs, and indirectly modulates γ-globin gene expression in these cells. Our findings provide important clues for further evaluations of CVA as a potential fetal hemoglobin therapeutic inducer.

GRIM19 ameliorates acute graft-versus-host disease (GVHD) by modulating Th17 and Treg cell balance through down-regulation of STAT3 and NF-AT activation.

BackgroundT helper (Th) 17 cells are a subset of T helper cells that express interleukin (IL)-17 and initiate the inflammatory response in autoimmune diseases. Regulatory T cells (Tregs) are a subpopulation of T cells that produce forkhead box P3 (FOXP3) and inhibit the immune response. Graft versus host disease (GVHD) is a complication of allogeneic tissue transplantation, and Th17 cells and their proinflammatory activity play a central role in the pathogenesis of GVHD. Gene associated with retinoid-interferon-induced mortality (GRIM) 19, originally identified as a nuclear protein, is expressed ubiquitously in various human tissues and regulate signal transducer and activator of transcription (STAT)3 activity.MethodsSplenoytes and bone marrow cells were transplanted into mice with GVHD. The alloresponse of T cells and GVHD clinical score was measured. Realtime-polymerase chain reaction (realtime-PCR) was used to examine mRNA level. Flow cytometry and enzyme linked immunosorbent assay (ELISA) was used to evaluate protein expression.ResultsA GRIM19 transgenic cell transplant inhibited Th17 cell differentiation, alloreactive T cell responses, and STAT3 expression in mice with GVHD. On the other hand, the differentiation of Tregs and STAT5 production were enhanced by GRIM19. Overall, the severity of GVHD was decreased in mice that had received GRIM19 transgenic bone marrow and spleen transplants. Transplantation from GRIM19-overexpressing cells downregulated the expression of nuclear factor of activated T cells (NFATc1) but promoted the expression of regulator of calcineurin (RCAN)3 while downregulating NFAT-dependent cytokine gene expression. This complex mechanism underlies the therapeutic effect of GRIM19.ConclusionsWe observed that GRIM19 can reduce Th17 cell differentiation and alloreactive T cell responses in vitro and in vivo. Additionally, GRIM19 suppressed the severity of GVHD by modulating STAT3 activity and controlling Th17 and Treg cell differentiation. These results suggest that GRIM19 attenuates acute GVHD through the inhibition of the excessive inflammatory response mediated by T cell activation.

Cis-vaccenic acid induces differentiation and up-regulates gamma globin synthesis in K562, JK1 and transgenic mice erythroid progenitor stem cells

Gamma globin induction remains a promising pharmacological therapeutic treatment mode for sickle cell anemia and beta thalassemia, however Hydroxyurea remains the only FDA approved drug which works via this mechanism. In this regard, we assayed the γ-globin inducing capacity of Cis-vaccenic acid (CVA). CVA induced differentiation of K562, JK1 and transgenic mice primary bone marrow hematopoietic progenitor stem cells. CVA also significantly up-regulated γ-globin gene expression in JK-1 and transgenic mice bone marrow erythroid progenitor stem cells (TMbmEPSCs) but not K562 cells without altering cell viability. Increased γ-globin expression was accompanied by KLF1 suppression in CVA induced JK-1 cells. Erythropoietin induced differentiation of JK-1 cells 24h before CVA induction did not significantly alter CVA induced differentiation and γ-globin expression in JK-1 cells. Inhibition of JK-1 and Transgenic mice bone marrow erythroid progenitor stem cells Fatty acid elongase 5 (Elovl5) and Δ9 desaturase suppressed the γ-globin inductive effects of CVA. CVA treatment failed to rescue γ-globin expression in Elovl5 and Δ9-desaturase inhibited cells 48h post inhibition in JK-1 cells. The data suggests that CVA directly modulates differentiation of JK-1 and TMbmEPSCs, and indirectly modulates γ-globin gene expression in these cells. Our findings provide important clues for further evaluations of CVA as a potential fetal hemoglobin therapeutic inducer

Modeling of Chronic Myeloid Leukemia: An Overview of In Vivo Murine and Human Xenograft Models.

Over the past years, a wide variety of in vivo mouse models have been generated in order to unravel the molecular pathology of Chronic Myeloid Leukemia (CML) and to develop and improve therapeutic approaches. These models range from (conditional) transgenic models, knock-in models, and murine bone marrow retroviral transduction models followed by transplantation. With the advancement of immunodeficient xenograft models, it has become possible to use human stem/progenitor cells for in vivo studies as well as cells directly derived from CML patients. These models not only mimic CML but also have been instrumental in uncovering various fundamental mechanisms of CML disease progression and tyrosine kinase inhibitor (TKI) resistance. With the availability of iPSC technology, it has become feasible to derive, maintain, and expand CML subclones that are at least genetically identical to those in patients. The following review provides an overview of all murine as well as human xenograft models for CML established till date.

Effects of cartilage-derived morphogenetic protein 1 (CDMP1) transgenic mesenchymal stem cell sheets in repairing rabbit cartilage defects.

The aim of this study was to investigate the abilities of cartilage-derived morphogenetic protein 1 (CDMP1) transgenic cell sheets in repairing rabbit cartilage defects. Rabbit CDMP1 transgenic bone marrow mesenchymal stem cell (BMSC) sheets (CDMP1-BMSCs) were cultured on temperature-sensitive culture dishes, and CDMP1 expression and type II collagen protein in the cell sheets were detected. Tissue-engineered cell sheets were constructed and transplanted into defect rabbit thyroid cartilage, to investigate the expression of engineered cartilage collagen protein and proteoglycan (GAG). The experiment was divided into three groups; A) BMSC sheet, B) Ad-CMV-eGFP-transfected cell sheet, and C) Ad-CMV-hCDMP1-IRES-eGFP-transfected cell sheet. The expression of CDMP1 was detected in the transgenic cell sheets. The engineered cartilage exhibited positive immunohistochemical and Alcian blue staining. The expression levels of type II collagen protein and GAG in group A were positive, whereas those in group B and group C were negative (P < 0.05). The CDMP1-BMSC sheets had a good cartilage differentiation activity, and could effectively repair rabbit laryngeal cartilage defects.