Mast Cells and Tumor Progression.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. SCI-33-SCI-33
Author(s):  
D. Wade Clapp ◽  
Fengchun Yang ◽  
David A. Ingram ◽  
Kent A. Robertson ◽  
Gary D. Hutchins ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Mast Cells ◽  
Schwann Cell ◽  
Tumor Progression ◽  
Schwann Cells ◽  
Plexiform Neurofibroma ◽  
Genetically Engineered ◽  
Cell Functions ◽  
Kit Ligand ◽  
Genetically Engineered Mice

Abstract Abstract SCI-33 Interactions between tumorigenic cells and their surrounding microenvironment are critical for tumor progression yet remain incompletely understood. Germline mutations in the NF1 tumor suppressor gene cause neurofibromatosis type 1 (NF1), a common genetic disorder characterized by complex tumors called neurofibromas. Neurofibromas form in association with peripheral nerves and are composed of Schwann cells, blood vessels, fibroblasts and degranulating mast cells. Genetic studies in engineered mice indicate that biallelic loss of Nf1 is required in the tumorigenic cell of origin in the embryonic Schwann cell lineage. However, in the physiologic state, Schwann cell loss of heterozygosity is not sufficient for neurofibroma formation in a genetically engineered murine model and Nf1 haploinsufficiency in at least one additional nonneoplastic lineage is required for tumor progression. Recent studies in our group have focused on evaluating the role of bone marrow-derived cells, and particularly mast cells, in the tumor microenvironment. Previous work by our group established that human and murine Nf1 deficient Schwann cells secrete high concentrations of kit-ligand. Kit-ligand has a central role in multiple mast cell functions including chemotaxis, proliferation and degranulation. In a series of bone marrow transplantation studies, we established that Nf1 haploinsufficiency in bone marrow is sufficient to allow neurofibroma progression in the context of Schwann cell Nf1 deficiency. Further, genetic or pharmacologic attenuation of c-kit signaling diminishes neurofibroma initiation and progression. Collectively, the studies implicate mast cells as active participants in tumor formation and identify therapeutic targets for human phase 1-2 clinical trials. Disclosures Off Label Use: The drug imatinib mesylate was used to treat plexiform neurofibromas in genetically engineered mice, in a child with a plexiform neurofibroma, and it is currently being tested in a phase 2 clinical trial.

Mast Cells Are Integral Components of the Tumor Microenvironment That Are Required for Plexiform Neurofibroma Progression.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 677-677
Author(s):  
Fengchun Yang ◽  
David A. Ingram ◽  
Shi Chen ◽  
Jin Yuan ◽  
Xiaohong Li ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Mast Cell ◽  
Mast Cells ◽  
Tumor Microenvironment ◽  
Tumor Progression ◽  
Schwann Cells ◽  
Plexiform Neurofibroma ◽  
Hematopoietic System ◽  
Plexiform Neurofibromas

Abstract Interactions between tumorigenic cells and the microenvironment are increasingly recognized as integral to tumor progression in a range of human malignancies. However, the specific cellular mechanisms that are required to initiate these multistage processes are incompletely understood. Mutations in the NF1 tumor suppressor gene cause neurofibromatosis type 1, a pandemic autosomal dominant genetic disorder of the nervous system characterized by the development of neurofibromas. Neurofibromas are complex tumors composed of Schwann cells, fibroblasts, endothelial cells, and high concentrations of degranulating mast cells. Though neurofibromas are generally benign, plexiform neurofibromas can progress to malignancy. Genetic studies in cre/lox mice indicate that nullizygous loss of Nf1 in the tumorigenic Schwann cells (Krox20; Nf1flox/flox) is necessary, but not sufficient for neurofibroma formation when the microenvironment is wildtype. However, neurofibromas form with 100% penetrance in Krox20; Nf1flox/− mice that are heterozygous at Nf1 in all lineages of the tumor microenvironment (Science, 2002). Here, we addressed the role of the hematopoietic system in the tumor microenvironment by using adoptive transfer. Syngeneic Nf1+/− or wildtype (WT) bone marrow was transplanted into lethally irradiated Krox20;Nf1flox/flox mice. Krox20; Nf1flox/flox recipients transplanted with WT bone marrow (n=25) did not develop plexiform neurofibromas and had a normal lifespan. In contrast, Krox20; Nf1flox/flox mice transplanted with Nf1+/− bone marrow (n=25) consistently developed neurofibromas infiltrated with Nf1+/− mast cells. These mice had a 90% mortality at 14 months following transplantation. In complementary experiments, WT bone marrow was transplanted into irradiated Krox20; Nf1flox/− mice. Despite the remainder of the tumor microenvironment being heterozygous, WT bone marrow was sufficient to prevent tumor progression in Krox20; Nf1flox/− mice. To specifically assess the role of the mast cell compartment in tumor progression, Nf1+/− mice were intercrossed with two strains of naturally occurring W mutant mice that have variably diminished c-kit activity and mast cell function. Mice homozygous at the Wv locus have a greater than 90% reduction in c-kit activity, while W41/W41 mutants have approximately a 65–75% reduction in c-kit activity. Importantly, while Krox20;Nf1flox/flox mice transplanted with Nf1+/− bone marrow consistently develop plexiform neurofibromas, adoptive transfer of Nf1+/−; Wv/Wv or Nf1+/−; W41/W41 bone marrow cells into Krox20; Nf1flox/flox mice was sufficient to prevent neurofibroma formation. Collectively, these studies provide genetic evidence that the hematopoietic system and specifically mast cells are integral to plexiform neurofibroma formation in genetically engineered mice. These studies have therapeutic implications for NF1 since molecular therapies directed at the haploinsufficient hematopoietic cells, particularly the c-kit receptor tyrosine kinase, may have an important role in treating or preventing plexiform neurofibromas.

scholarly journals The immediate phase of c-kit ligand stimulation of mouse bone marrow-derived mast cells elicits rapid leukotriene C4 generation through posttranslational activation of cytosolic phospholipase A2 and 5-lipoxygenase.

1995 ◽  
Vol 182 (1) ◽  
pp. 197-206 ◽  
Author(s):  
M Murakami ◽  
K F Austen ◽  
J P Arm
Keyword(s):  
Bone Marrow ◽  
Arachidonic Acid ◽  
Mast Cells ◽  
Cell Membrane ◽  
Phospholipase A2 ◽  
Mouse Bone Marrow ◽  
Kit Ligand ◽  
Cytosolic Phospholipase ◽  
Delayed Phase ◽  
Stimulation Of

c-kit ligand (KL) activated mouse bone marrow-derived mast cells (BMMC) for the dose- and time-dependent release of arachidonic acid from cell membrane phospholipids, with generation of leukotriene (LT) C4 in preference to prostaglandin (PG)D2. KL at concentrations of 10 ng/ml elicited half-maximal eicosanoid generation and at concentrations of > 50 ng/ml elicited a maximal generation of approximately 15 ng LTC4 and 1 ng PGD2 per 10(6) cells, with 20% net beta-hexosaminidase release 10 min after stimulation. Of the other cytokines tested, none, either alone or in combination with KL, elicited or modulated the immediate phase of mediator release by BMMC, indicating strict specificity for KL. Activation of BMMC in response to KL was accompanied by transient phosphorylation of cytosolic phospholipase A2 and reversible translocation of 5-lipoxygenase to a cell membrane fraction 2-5 min after stimulation, when the rate of arachidonic acid release and LTC4 production were maximal. BMMC continuously exposed to KL in the presence of IL-10 and IL-1 beta generated LTC4 in marked preference to PGD2 over the first 10 min followed by delayed generation of PGD2 with no LTC4 over several hours. Pharmacologic studies revealed that PGD2 generation in the immediate phase depended on prostaglandin endoperoxide synthase (PGHS)-1 and in the delayed phase on PGHS-2. Thus, KL provided a nonallergic stimulus for biphasic eicosanoid generation by mast cells. The immediate phase is dominated by LTC4 generation with kinetics and postreceptor biosynthetic events similar to those observed after cell activation through the high affinity IgE receptor, whereas the delayed phase of slow and selective PGD2 production is mediated by induction of PGHS-2.

scholarly journals Dependence on Schwann Cell-Derived Laminin-γ1 Differentiates Early Lymphoid and Myeloid Development

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 37-37
Author(s):  
Kristin Komnick ◽  
Jennifer May ◽  
Pouneh Kermani ◽  
Sreemanti Basu ◽  
Irene Hernandez ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Nervous System ◽  
Schwann Cell ◽  
Peripheral Nerve ◽  
Peripheral Nervous System ◽  
Schwann Cells ◽  
Adrenergic Nerve ◽  
Spleen Size ◽  
Mouse Line ◽  
Myeloid Development

Blood cell production is regulated by peripheral nerve fibers that innervate the bone marrow. However, little is known about the development or maintenance of hematopoietic innervation. Schwann cells (SCs) are the primary axon 'support cells' of the peripheral nervous system (PNS), and abnormal SC development is sufficient to impair peripheral nerve function. SCs are also the primary repair cell for the PNS which makes them an attractive therapeutic target for normalization of drug or malignancy-induced 'hematopoietic neuropathy'. We hypothesized that neural regulation of hematopoiesis is dependent on SC development. To test this hypothesis, we used the Myelin Protein Zero-Cre (MP0-Cre); Lamc1fl/fl mouse line in which laminin-γ1 expression is deleted from SC precursors and their progeny1. Early SC maturation is dependent on autocrine SC precursor-derived molecules such as laminin-γ1. SC differentiation arrests prior to axon sorting and ensheathment in MP0-Cre; Lamc1fl/fl mice, and causes a global peripheral neuropathy that persists throughout the lifetime of the animal. Preliminary hematopoietic analysis of 'steady state' MP0-Cre; Lamc1fl/fl and littermate control mice has shown the following: (1) MP0-Cre; Lamc1fl/fl bone marrow is innervated, and Cre-mediated gene recombination occurs in cells immunophenotypically consistent with SCs throughout the peripheral nervous system, including those in the bone marrow; (2) MP0-Cre; Lamc1fl/fl mice are lymphopenic but not neutropenic; (3) MP0-Cre; Lamc1fl/fl mice have significantly reduced spleen size and cellularity; and (4) MP0-Cre; Lamc1fl/fl bone marrow has an ~50% reduction in Lin-Sca-1+Kit+(LSK) cells (measured as a percentage of the Lin- compartment of the bone marrow). These results are consistent with earlier work by our groups in which we found that global Lamc1 gene deletion in adult mice induced peripheral blood lymphopenia, reduced spleen size, and a niche-dependent reduction of lymphoid progenitor and precursor cells that was secondary to increased lymphoid precursor cell apoptosis and reduced proliferation (UBC-CreERT2; Lamc1fl/fl mouse line). As with the SC-specific laminin-γ1 deficient mice, myelopoiesis was preserved in the UBC-CreERT2; Lamc1fl/fl mice. Based on results from MP0-Cre; Lamc1fl/fl and UBC-CreERT2; Lamc1fl/fl mice, we conclude that early lymphoid but not myeloid development requires laminin-γ1 expression by MP0-Cre-targetted niche cells, i.e. Schwann Cells. Our results are consistent with reports from other labs that hematopoietic sympathetic neuropathy promotes aberrant myeloid expansion at the expense of lymphopoiesis2. Going forward, we will determine whether lymphopoietic development is dependent on global versus laminin-specific SC-derived cues, and whether these signals are transmitted directly between SCs and lymphoid biased HSPCs or indirectly via other components of the hematopoietic niche. We anticipate that this line of investigation will provide molecular insights and pharmacologic targets for prevention and or normalization of the 'hematopoietic neuropathy' induced by diabetes, aging, neurotoxic chemotherapies and myeloid malignancies. REFERENCES: 1 Yu, W. M., Feltri, M. L., Wrabetz, L., Strickland, S. & Chen, Z. L. Schwann cell-specific ablation of laminin gamma1 causes apoptosis and prevents proliferation. J Neurosci25, 4463-4472, doi:10.1523/JNEUROSCI.5032-04.2005 (2005). 2 Maryanovich, M. et al. Adrenergic nerve degeneration in bone marrow drives aging of the hematopoietic stem cell niche. Nat Med24, 782-791, doi:10.1038/s41591-018-0030-x (2018). Disclosures No relevant conflicts of interest to declare.

Adoptive Transfer of Nf1+/− Bone Marrow Is Sufficient for Neurofibroma Progression in Krox20;Nf1flox/flox Mice.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3064-3064
Author(s):  
Fengchun Yang
Keyword(s):  
Bone Marrow ◽  
Mast Cells ◽  
Tumor Microenvironment ◽  
Schwann Cells ◽  
Genetic Disorder ◽  
Hematopoietic Cells ◽  
Tumor Formation ◽  
Conditional Knockout ◽  
Axial Tomography

Abstract Mutations in the NF1 tumor suppressor gene cause neurofibromatosis type 1 (NF1), a GTPase activating protein for Ras called neurofibromin. NF1 is a genetic disorder that affects approximately 250,000 individuals in the US, Europe, and Japan alone. Neurofibromas, the hallmark of NF1, are complex tumors characterized by tumorigenic Schwann cells, neoangiogenesis, fibrosis, and degranulating mast cells. Studies in experimental models have emphasized the role of inflammatory cells in altering the microenvironment and facilitating malignant outgrowth. Similarly, Parada (Science, 2002) found that nullizygosity of Nf1 in Schwann cells of conditional knockout mice (Krox20;Nf1flox/flox) was necessary but not sufficient for neurofibroma formation and haploinsufficiency of Nf1 in lineages within the tumor microenvironment was required for neurofibroma progression. We previously provided the first genetic, cellular, and biochemical evidence that haploinsufficiency of Nf1 alters Ras activity and cell fates in mast cells (JEM, 2000, 2001) and identified a mechanism underlying the recruitment of mast cells to tumorigenic Schwann cells (JCI 2003). However, it remains unclear whether Nf1 +/− bone marrow derived hematopoietic cells can directly contribute to neurofibroma formation in vivo. To address this question, Nf1+/− or wildtype (WT) EGFP+ bone marrow (BM) was adoptively transferred into lethally irradiated Krox20;Nf1flox/flox mice and cohorts were followed prospectively for tumor formation using positron emission tomography and computerized axial tomography. Mice transplanted with Nf1+/− but not WT BM developed progressive enlargement of the trigeminal nerve, dorsal root ganglia, peripheral nerves, and motor paralysis similar to Krox20;Nf1flox/− mice that are haploinsufficient at Nf1 in all lineages of the tumor microenvironment. Postmortem analysis revealed that Krox20;Nf1flox/flox mice transplanted with Nf1+/− BM had cellular neurofibromas containing Schwann cells, fibroblasts, blood vessels and mast cells, which closely resembled the cellular architecture of human neurofibromas. Mice transplanted with WT BM did not develop neurofibromas. These studies establish that recruitment of Nf1 +/− BM derived cells to the neurofibroma microenvironment is directly linked to neurofibroma formation and progression. Given our observations, therapies which prevent both the recruitment and the tumor promoting functions of Nf1 +/− hematopoietic cells in neurofibroma formation are currently being tested in vivo as pre-clinical trials.

Differential Role of Class 1A PI 3-Kinase Regulatory Subunits in Mast Cell Growth, Maturation and Survival.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 77-77
Author(s):  
Raghuveer Mali ◽  
Subha Krishnan ◽  
Ramdas Baskar ◽  
Veerendra Munugalavadla ◽  
Emily Sims ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Mast Cell ◽  
Mast Cells ◽  
Bone Marrow Cells ◽  
Full Length ◽  
Receptor Internalization ◽  
Regulatory Subunits ◽  
Growth And Survival ◽  
Cell Functions ◽  
Kit Receptor

Abstract Abstract 77 Stem cell factor (SCF) mediated c-Kit receptor activation plays a pivotal role in mast cell growth, maturation and survival. However, the signaling events downstream from c-Kit are poorly understood. Mast cells express multiple regulatory subunits of class 1A PI 3-kinase including p85α, p85β, p50α, and p55α. While it is known that PI 3-kinase plays an essential role in mast cells; the precise mechanism by which these regulatory subunits impact specific mast cell functions including maturation, growth, and survival are not known. Using mice deficient in the expression of p85α or p85β or combination of both p85α/p55α/p50α as well as all four subunits we have examined the role of these subunits in mast cell functions. We show that loss of p85α subunit alone results in impaired bone marrow derived mast cell (BMMC) maturation, growth, and survival compared to wild-type (WT) controls, in spite of the continuous expression of p85β, p55α, and p50α subunits in these cells. Restoring the expression of p85α in p85α deficient mast cells restores the maturation and growth defects. To assess the contribution of p50α and p55α subunits, we generated mice using the Cre lox system that were deficient in the expression of all three subunits (i.e. p85α/p55α/p50α). Deficiency of p85α/p55α/p50α subunits in bone marrow cells completely blocked mast cell maturation and growth, suggesting an essential role for the smaller subunits p50 and p55 in addition to the full length form of p85. Curiously, over-expression of p50α in p85α deficient BMMCs only marginally rescued mast cell maturation and growth, suggesting that the full length form of p85α functions with specificity in regulating mast cell functions. Since the major difference between the shorter isoforms and the full length form of p85α is the absence of the amino terminal SH3 and BH domains, we generated two mutants of p85α lacking either the SH3 or the BH domain and expressed them in p85α−/− BMMCs. While both these mutants completely restored the maturation defect associated with p85α deficiency and showed normal binding to the c-Kit receptor upon SCF stimulation as well as to the p110 catalytic subunits; none of these mutants completely rescued SCF induced proliferation (50% and 70% respectively, n=3, p<0.004). Biochemically, lack of SCF induced growth rescue in p85α−/− BMMCs expressing p85αΔSH3 and p85αΔBH mutants was associated with a lack of rescue in the activation of Akt and Erk, but complete rescue in the activation of JNK (n=3). Consistently, while transplantation of p85α deficient bone marrow cells transduced with p85α into mast cell deficient Wsh mice resulted in complete restoration of gastrointestinal mast cells as well as mast cells in the stomach and spleen, p85αΔSH3 and p85αΔBH mutants restored mast cells only partially. These results indicate that other domains (SH3 and BH) of p85α are required for mast cell growth. In contrast to p85α, deficiency of p85β alone resulted in increased BMMC maturation, growth and survival compared to controls (1.2 fold, n=3, p<0.003). Consistently, over-expression of p85β in WT bone marrow cells resulted in a profound reduction in the maturation of mast cells as well as proliferation. We studied whether reduced maturation and proliferation due to the loss or over-expression of p85β was a result of altered c-Kit receptor internalization and degradation. Our results revealed significantly more c-Kit receptor internalization and degradation in p85β expressing cells compared to p85α expressing cells (2 fold, n=5, p<0.001). Since Cbl family of ubiquitin ligases are involved in the down-regulation of tyrosine kinase receptors, we analyzed whether c-Cbl is involved in p85β mediated c-Kit receptor internalization and degradation. Phosphorylation of c-Cbl and ubiquitination of c-Kit receptor was more in p85β expressing cells compared to p85 expressing cells (n=3). In conclusion, while the current dogma in the field of PI3Kinase signaling suggests that all regulatory subunits of PI3Kinase function in a similar manner; we provide genetic and biochemical evidence to suggest that p85 regulatory subunits differentially regulate growth and maturation of mast cells. Disclosures: Munugalavadla: Genentech: Employment, Patents & Royalties.

scholarly journals Muscle Satellite Cells and Endothelial Cells: Close Neighbors and Privileged Partners

2007 ◽  
Vol 18 (4) ◽  
pp. 1397-1409 ◽  
Author(s):  
Christo Christov ◽  
Fabrice Chrétien ◽  
Rana Abou-Khalil ◽  
Guillaume Bassez ◽  
Grégoire Vallet ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Endothelial Cells ◽  
Capillary Density ◽  
Genetically Engineered ◽  
Amyopathic Dermatomyositis ◽  
Normal Muscle ◽  
Muscle Satellite Cell ◽  
Genetically Engineered Mice ◽  
Unique Condition

Genetically engineered mice (Myf5nLacZ/+, Myf5GFP-P/+) allowing direct muscle satellite cell (SC) visualization indicate that, in addition to being located beneath myofiber basal laminae, SCs are strikingly close to capillaries. After GFP+ bone marrow transplantation, blood-borne cells occupying SC niches previously depleted by irradiation were similarly detected near vessels, thereby corroborating the anatomical stability of juxtavascular SC niches. Bromodeoxyuridine pulse-chase experiments also localize quiescent and less quiescent SCs near vessels. SCs, and to a lesser extent myonuclei, were nonrandomly associated with capillaries in humans. Significantly, they were correlated with capillarization of myofibers, regardless to their type, in normal muscle. They also varied in paradigmatic physiological and pathological situations associated with variations of capillary density, including amyopathic dermatomyositis, a unique condition in which muscle capillary loss occurs without myofiber damage, and in athletes in whom capillaries increase in number. Endothelial cell (EC) cultures specifically enhanced SC growth, through IGF-1, HGF, bFGF, PDGF-BB, and VEGF, and, accordingly, cycling SCs remained mainly juxtavascular. Conversely, differentiating myogenic cells were both proangiogenic in vitro and spatiotemporally associated with neoangiogenesis in muscular dystrophy. Thus, SCs are largely juxtavascular and reciprocally interact with ECs during differentiation to support angio-myogenesis.

Lack of neurokinin-1 receptor expression affects tissue mast cell numbers but not their spatial relationship with nerves

2005 ◽  
Vol 288 (2) ◽  
pp. R491-R500 ◽  
Author(s):  
Michael R. D'Andrea ◽  
Marcia R. Saban ◽  
Norma P. Gerard ◽  
Barry K. Wershil ◽  
Ricardo Saban
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Spatial Association ◽  
Spatial Relationship ◽  
Genetically Engineered ◽  
Receptor Expression ◽  
Wild Type ◽  
Genetically Engineered Mice ◽  
Neurokinin 1 ◽  
Anatomic Relationship

A spatial association between mast cells and nerves has been described in both the gastrointestinal and genitourinary tracts. However, the factors that influence the anatomic relationship between mast cells and nerves have not been completely defined. It has been suggested that the high-affinity receptor for substance P [neurokinin-1 (NK1)] might modulate this interaction. We therefore assessed mast cell-nerve relationships in tissues isolated from wild-type and NK1 receptor knockout (NK1−/−) mice. We now report that, in the complete absence of NK1 receptor expression, there is a significant increase in the number of mast cells without a change in the anatomic relationship between mast cell and nerves in stomach and bladder tissues at the light microscopic level. We next determined whether transplanted mast cells would maintain their spatial distribution, number, and contact with nerve elements. For this purpose, mast cell-deficient Kit W /Kit W−v mice were reconstituted with wild-type or NK1−/− bone marrow. No differences in mast cell-nerve contact were observed. These results suggest that NK1 receptor expression is important in the regulation of the number of mast cells but is not important in the interaction between mast cells and nerves. Furthermore, the interaction between mast cells and nerves is not mediated through NK1 receptor expression on the mast cell. Further studies are needed to determine the molecular pathway involved in mast cell migration and interaction with nerve elements, but the model of reconstitution of Kit W /Kit W−v mice with mast cells derived from different genetically engineered mice is a useful approach to further explore these mechanisms.

Murine and Human NF1 Haploinsufficient Mast Cells Promote Alterations in Fibroblast Function and Organization of the Extracellular Matrix in Three-Dimensional Collagen Lattices and this Gain in Function Is Abrogated by the Addition of STI-571.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1465-1465
Author(s):  
Fengchun Yang ◽  
Clegg Travis ◽  
Shi Chen ◽  
Xiaohong Li ◽  
Selina A. Estwick ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Endothelial Cells ◽  
Mast Cells ◽  
Tumor Microenvironment ◽  
Schwann Cells ◽  
Collagen Synthesis ◽  
Three Dimensional ◽  
Fibroblast Migration ◽  
Kit Ligand ◽  
Collagen Lattices

Abstract Cutaneous neurofibromas are a hallmark of neurofibromatosis type 1 (NF1), a common genetic disorder that is caused by mutations in the NF1 gene, which functions as a GAP for p21ras. Though the pathogenesis of neurofibroma formation is not completely known, haploinsufficiency of the nonneuronal lineages (fibroblasts, mast cells and endothelial cells) in the tumor microenvironment are required for neurofibroma formation (Zhu, Science 2002). These tumors are characterized by a high concentration of degranulating mast cells (MC) closely associated with fibroblasts, endothelial cells and Schwann cells. We have recently shown that Nf1−/− Schwann cells secrete kit-ligand to recruit Nf1+/− MCs to the tumor microenvironment via hyperactivation of a p21ras-PI3K-Rac dependent pathway (Yang, JCI 2003). Further, Nf1+/− MC also promote Schwann cell invasion and proliferation. Given that collagen is synthesized by fibroblasts and is approximately 80% of the weight of neurofibromas, we tested whether Nf1+/− MC promote the proliferation and collagen synthesis of fibroblasts. Strikingly, the proliferation of Nf1+/− fibroblasts in response to Nf1+/− MC conditioned media (MCCM) was 3 fold higher than any other group tested. In a wound healing assay Nf1+/− MCCM provided potent stimulus for the migration of Nf1+/− but not WT fibroblasts. Similarly, MCCM from primary human NF1+/− MC stimulated the proliferation, migration, and collagen synthesis of human NF1+/− fibroblasts, validating that our observations in Nf1+/− murine cells faithfully phenocopy the biology of human NF1 heterozygous cells. We next established three dimensional collagen lattices containing MC and fibroblasts of the respective genotypes to evaluate extracellular matrix (ECM) reorganization given that remodeling of the ECM by inflammatory cells promotes tumorigenesis. Histological examination revealed that while MC and fibroblasts of both genotypes localized to each other, there was a 2–3 fold quantitative increase in the localization or attachment of Nf1+/− MC to Nf1+/− fibroblasts. Further, Nf1+/− MC preferentially promoted a 2–3 fold increase in the lattice contraction indicative of alteration of the ECM in lattices containing either Nf1+/− or WT fibroblasts. Given that c-kit/kit-ligand interactions between MC and fibroblasts contribute to MC-fibroblast interactions, c-kit blocking antibodies or Gleevec, an antitumor drug that inhibits both BCR/ABL and c-kit tyrosine kinases, were added to MC-fibroblast cultures. Both of these agents blocked the activity of Nf1+/− MC on fibroblast proliferation, collagen remodeling and fibroblast migration. Collectively, these studies demonstrate that murine and human NF1 (Nf1) haploinsufficient MC stimulate the proliferation, migration, collagen synthesis of Nf1+/− fibroblasts as well as remodeling the ECM. This study provides strong evidence that Gleevec may be a candidate therapy for the treatment or prevention of neurofibromas.

scholarly journals Effects of stem cell factor (kit-ligand) and interleukin-3 on the growth and serine proteinase expression of rat bone-marrow-derived or serosal mast cells

Blood ◽  
1994 ◽  
Vol 83 (1) ◽  
pp. 72-83 ◽  
Author(s):  
DM Haig ◽  
JF Huntley ◽  
A MacKellar ◽  
GF Newlands ◽  
L Inglis ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Stem Cell ◽  
Mast Cells ◽  
Stem Cell Factor ◽  
Synergistic Effects ◽  
Serine Proteinase ◽  
In Vitro Growth ◽  
Interleukin 3 ◽  
Kit Ligand

Abstract The effects of rat stem-cell factor (SCF) and interleukin-3 (IL-3), alone or in combination, on the in vitro growth and serine proteinase expression of rat serosal/connective-tissue mast cells (CTMC) or bone marrow-derived mast cells (BMMC) were examined. Rat SCF stimulated the growth of both CTMC and BMMC. IL-3 stimulated BMMC growth to a lesser extent than did SCF, whereas CTMC numbers did not increase in IL-3. However, SCF and IL-3 had synergistic effects on the growth of both BMMC and CTMC. SCF favoured the maintenance of rat mast cell proteinase- I (RMCP-I) in CTMC, but did not induce detectable production of RMCP-I in BMMC. In contrast, when IL-3 or lymph node-conditioned medium (LNCM) was added to SCF, a subpopulation of CTMC expressed and stored the soluble proteinase RMCP-II. In BMMC, the RMCP-II content of cells maintained in SCF was significantly less than that of cells maintained in IL-3 or LNCM. RMCP-II also appeared in the supernatants of BMMC, especially when BMMC numbers were increasing rapidly in SCF with or without IL-3 or LNCM. Thus, SCF and IL-3 can regulate the growth of rat BMMC and CTMC, as well as influence their production and release of proteinases.

scholarly journals Basophils, a neglected minority in the immune system, have come into the limelight at last

2021 ◽  
Author(s):  
Hajime Karasuyama ◽  
Sho Shibata ◽  
Soichiro Yoshikawa ◽  
Kensuke Miyake
Keyword(s):  
Mast Cells ◽  
Protective Immunity ◽  
Animal Studies ◽  
Genetically Engineered ◽  
Parasitic Infections ◽  
Genetically Engineered Mice ◽  
Analytical Tools ◽  
Human Basophils ◽  
Paul Ehrlich ◽  
New Strategies

Abstract Basophils, the rarest granulocytes, were identified by Paul Ehrlich more than 140 years ago, much earlier than the discovery of T and B cells. Unfortunately, basophils were often mixed up with tissue-resident mast cells because of some phenotypic similarities between them and considered erroneously as minor relatives or blood-circulating precursors of mast cells. Moreover, basophil research was hindered by the rarity of basophils and the paucity of useful analytical tools, and therefore basophils had often been neglected in immunological studies. A series of studies using newly developed tools, including basophil-depleting antibodies and genetically engineered mice deficient only in basophils, have clearly defined previously unrecognized roles of basophils, that are distinct from those played by tissue-resident mast cells. In this mini-review, we highlight recent advances in our understanding of basophil functions, particularly focusing on their roles in the regulation of innate and acquired immunity, allergic reactions, autoimmunity and protective immunity against parasitic infections, mainly based on animal studies. Further studies on human basophils would facilitate the development of new strategies for the treatment of basophil-associated disorders.

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