Jonathan P. Arm, M.D., M.R.C.P.

Specialty: Allergy

Brigham and Women’s Hospital

Smith Research Bldg., Rm 638
1 Jimmy Fund Way
Boston, MA 02115


The following is a list of recent publications for which this Partners Asthma Center physician has been cited as an author in PubMed databases. Study abstracts have been provided for your convenience.

Tedla, N., C. Bandeira-Melo, et al. (2003). "Activation of human eosinophils through leukocyte immunoglobulin-like receptor 7." Proc Natl Acad Sci U S A 100(3): 1174-9.

Eosinophils are implicated prominently in allergic diseases and the host response to parasitic infections. Eosinophils may be activated in vitro by diverse classes of agonists such as immunoglobulins, lipid mediators, and cytokines. The leukocyte Ig-like receptors (LIRs) comprise a family of inhibitory and activating cell-surface receptors. Inhibitory LIRs down-regulate cellular responses through cytoplasmic immunoreceptor tyrosine-based inhibitory motifs. There are limited data on the action of the activating LIRs, which are thought to signal through the Fc receptor gamma chain, which contains an immunoreceptor tyrosine-based activation motif. We now demonstrate the expression of LIR1 (inhibitory), LIR2 (inhibitory), LIR3 (inhibitory), and LIR7 (activating) on eosinophils from 4, 4, 12, and 11, respectively, of 12 healthy donors. Cross-linking of LIR7 with plate-bound antibody elicited the dose- and time-dependent release of eosinophil-derived neurotoxin and leukotriene C(4). Eosinophils activated with antibodies to LIR7 embedded in gel-phase EliCell preparations showed leukotriene C(4) generation at the nuclear envelope and the release of IL-12 but not IL-4 by vesicular transport. Thus, LIR7 is an activating receptor for eosinophils that elicited the release of cytotoxic granule proteins, de novo lipid mediator generation, and cytokine release through vesicular transport.

Lin, D. A. and J. P. Arm (2003). "Asthma or not? The value of flow volume loops in evaluating airflow obstruction." Allergy Asthma Proc 24(2): 107-10.

Large airway obstruction can present with symptoms typically associated with asthma, including cough, dyspnea, or wheezing. Obstruction of the large airways should be considered in the differential diagnosis of patients with difficult to manage asthma, particularly those with known risk factors for tracheal disease, atypical clinical features, or lack of response to standard asthma therapy. Spirometry and flow volume loops are valuable diagnostic tools in this evaluation. This article discusses two cases in which large airway obstruction mimicked asthma and reviews the characteristic flow volume loop patterns associated with large airway lesions.

Diaz, B. L. and J. P. Arm (2003). "Phospholipase a(2)." Prostaglandins Leukot Essent Fatty Acids 69(2-3): 87-97.

Considerable progress has been made in characterizing the individual participant enzymes and their relative contributions in the generation of eicosanoids, lipid mediators derived from arachidonic acid, such as prostaglandins and leukotrienes. However, the role of individual phospholipase (PL) A(2) enzymes in providing arachidonic acid to the downstream enzymes for eicosanoid generation in biologic processes has not been fully elucidated. In this review, we will provide an overview of the classification of the families of PLA(2) enzymes, their putative mechanisms of action, and their role(s) in eicosanoid generation and inflammation.

Arm, J. P. (2003). "Preface." Prostaglandins Leukot Essent Fatty Acids 69(2-3): 85.

Tedla, N., K. Gibson, et al. (2002). "The co-expression of activating and inhibitory leukocyte immunoglobulin-like receptors in rheumatoid synovium." Am J Pathol 160(2): 425-31.

Rheumatoid arthritis (RA) is a chronic inflammatory synovitis, with destruction of juxtaarticular cartilage and bone, likely mediated by lipid mediators, cytokines, and proteases released from inflammatory leukocytes. The mechanisms regulating leukocyte activation in rheumatoid synovium are not fully elucidated. A new family of cell surface proteins termed leukocyte immunoglobulin-like receptors (LIRs) has been shown in vitro to modulate cellular responses through immunoreceptor tyrosine-based inhibitory motifs or through association with the Fc receptor gamma chain that contains immunoreceptor tyrosine-based activation motifs. We studied the expression of inhibitory and activating LIRs in the synovium of six RA patients, three osteoarthritis patients, and three controls by immunohistochemistry. The synovium from patients with early RA showed extensive expression of the inhibitory LIR-2 and the activating LIR-7 on macrophages and neutrophils. Some mast cells and endothelial cells expressed LIR-7. There was limited expression of LIRs in synovium from two patients with long-standing RA, patients with osteoarthritis, and controls. LIR-2 recognizes MHC class I molecules. We therefore suggest that LIRs may regulate the activation of infiltrating leukocytes in synovial tissue and are a potential therapeutic target.

Diaz, B. L., H. Fujishima, et al. (2002). "Participation of cytosolic phospholipase A2 in eicosanoid generation by mouse bone marrow-derived mast cells." Adv Exp Med Biol 507: 41-6.

Diaz, B. L., H. Fujishima, et al. (2002). "Regulation of prostaglandin endoperoxide synthase-2 and IL-6 expression in mouse bone marrow-derived mast cells by exogenous but not endogenous prostanoids." J Immunol 168(3): 1397-404.

Mouse bone marrow-derived mast cells (BMMC), stimulated with stem cell factor, IL-1beta, and IL-10, secrete IL-6 and demonstrate a delayed phase of PGD(2) generation that is dependent upon the induced expression of PG endoperoxide synthase (PGHS)-2. We have examined the potential for exogenous prostanoids, acting in a paracrine fashion, and endogenous prostanoids, acting in an autocrine fashion, to regulate PGHS-2 induction and IL-6 secretion in mouse BMMC. Exogenous PGE(2), which acts through G protein-coupled receptors, and 15-deoxy-Delta(12,14)-PGJ(2), which is a ligand for peroxisome proliferator-activated receptor (PPAR)gamma, elicited a 2- to 3-fold amplification of PGHS-2 induction, delayed-phase PGD(2) generation, and IL-6 secretion in response to stem cell factor, IL-1beta, and IL-10. The effect of PGE(2) was reproduced by the E prostanoid (EP)1 receptor agonist 17-trinor-PGE(2), and the EP1/EP3 agonist, sulprostone, but not the EP2 receptor agonist, butaprost. Although BMMC express PPARgamma, the effects of 15-deoxy-Delta(12,14)-PGJ(2) were not reproduced by the PPARgamma agonists, troglitazone and ciglitazone. PGHS-2 induction, but not IL-6 secretion, was impaired in cPLA(2)-deficient BMMC. However, there was no impairment of PGHS-2 induction in BMMC deficient in hematopoietic PGD synthase or PGHS-1 in the presence or absence of the PGHS-2 inhibitor, NS-398. Thus, although exogenous prostanoids may contribute to amplification of the inflammatory response by augmenting PGD(2) generation and IL-6 secretion from mast cells, endogenous prostanoids do not play a role.

Arm, J. P. and K. F. Austen (2002). "Leukotriene receptors and aspirin sensitivity." N Engl J Med 347(19): 1524-6.

Ho, I. C., J. P. Arm, et al. (2001). "A novel group of phospholipase A2s preferentially expressed in type 2 helper T cells." J Biol Chem 276(21): 18321-6.

We report a novel phospholipase A(2) (PLA(2)), group XII (GXII) PLA(2), distinct from other cysteine-rich groups with a catalytic histidine motif, by its 20-kDa size and distribution of the 14 cysteine residues within the protein. Alternative spliced forms with distinct subcellular localization, designated GXII-1 and GXII-2, were identified by reverse transcription-polymerase chain reaction. Importantly, GXII PLA(2)s, in particular GXII-2 PLA(2), and group V PLA(2), but not group X PLA(2), were selectively expressed in murine type 2 helper T (Th2) clones and in vitro differentiated mouse CD4 Th2 cells as compared with type 1 helper T clones and cells. Stimulation with anti-CD3 appreciably up-regulated expression of GXII PLA(2)s and group V PLA(2) by steady state analysis of the Th2 cells as compared with type 1 helper T cells. These results suggest that group XII and group V PLA(2)s might participate in helper T cell immune response through release of immediate second signals and generation of downstream eicosanoids.

Sanchez Mejia, R. O., B. K. Lam, et al. (2000). "Matrix-associated transforming growth factor-beta1 primes mouse bone marrow-derived mast cells for increased high-affinity Fc receptor for immunoglobulin E-dependent eicosanoid biosynthesis." Am J Respir Cell Mol Biol 22(5): 557-65.

Mast cells at different tissue locations are heterogeneous with respect to histochemical staining characteristics, granule protease and proteoglycan content, and eicosanoid biosynthesis. We used Matrigel, an extract from the Engelbreth-Holm-Swarm mouse sarcoma that is enriched in basement-membrane proteins, to investigate the effect of tissue matrix proteins on the differentiation of mouse mast cells, with particular attention to eicosanoid biosynthesis. Culture of mouse bone-marrow cells in interleukin-3 on Matrigel for 3 to 4 wk provided a population of mast cells with more intense metachromasia and increased safranin counterstaining compared with mast cells derived in the absence of Matrigel (bone marrow-derived mast cells [BMMC]). High-affinity Fc receptor for immunoglobulin E-dependent biosynthesis of prostaglandin D(2) and leukotriene (LT) C(4) was 6- and 11-fold higher, respectively, from mast cells derived in the presence of Matrigel compared with conventional BMMC derived in its absence. BMMC derived in the presence of Matrigel also generated substantial quantities of 6-trans-LTB(4) diastereoisomers and LTB(4), which were minimally generated by conventional BMMC. When conventional BMMC derived in the absence of Matrigel were then cultured on Matrigel for 5 d, eicosanoid biosynthesis was upregulated without any change in granule staining characteristics. This upregulation in eicosanoid biosynthesis was inhibited by neutralizing anti- transforming growth factor (TGF)-beta1-specific antibodies, was reproduced by 1 ng/ml TGF-beta1, and was attributed to increased expression of cytosolic phospholipase A(2).

Liu, W. R., J. Kim, et al. (2000). "Genomic organization of the human leukocyte immunoglobulin-like receptors within the leukocyte receptor complex on chromosome 19q13.4." Immunogenetics 51(8-9): 659-69.

The leukocyte immunoglobulin (Ig)-like receptors (LIRs) comprise a family of cell surface receptors that couple to either activating or inhibitory signals depending on the nature of their transmembrane and cytoplasmic domains. We describe the organization and fine localization of the genes for LIR-1 and LIR-5, which are inhibitory receptors, and LIR-6, which is an activating receptor. The genomic organization of all three genes is highly conserved from the signal peptide through the membrane-proximal Ig domain but diverges thereafter depending on the inhibitory or activating nature of the gene product. The 3' untranslated region of the gene for LIR-6 contains a 37-base pair repeat not present in the LIR-1 or LIR-5 genes. 5' rapid amplification of cDNA ends defined the putative transcription initiation site of the LIR-5 gene, which is TATA-less. A nucleotide substitution in the LIR-5 gene led to loss of an intron present in the 5' untranslated region of the LIR-1 and LIR-6 genes. Differences in the genomic structure of these three LIR genes suggests possible mechanisms for their differential expression in cells of hematopoietic lineage. The three genes are in a region of Chromosome 19q13.4 that is immediately centromeric of the killer cell Ig-like receptor genes and are separated from one another by approximately 20 to 30 kb, suggesting that they arose by gene duplication from a common ancestor.

Fujishima, H., R. O. Sanchez Mejia, et al. (1999). "Cytosolic phospholipase A2 is essential for both the immediate and the delayed phases of eicosanoid generation in mouse bone marrow-derived mast cells." Proc Natl Acad Sci U S A 96(9): 4803-7.

We have used mice in which the gene for cytosolic phospholipase A2 (cPLA2) has been disrupted to demonstrate the absolute requirement for cPLA2 in both the immediate and the delayed phases of eicosanoid generation by bone marrow-derived mast cells. For the immediate phase, quantitative analysis of the products of the 5-lipoxygenase pathway showed that gene disruption of cPLA2 prevented the provision of arachidonic acid substrate for biosynthesis of proximal intermediates. By analogy, we conclude that arachidonic acid substrate was also not available to prostaglandin endoperoxide synthase 1 in the immediate phase of prostaglandin (PG) D2 generation. These defects occurred with two distinct stimuli, stem cell factor and IgE/antigen, which were, however, sufficient for signal transduction defined by exocytosis of beta-hexosaminidase. Whereas cPLA2 is essential for immediate eicosanoid generation by providing arachidonic acid, its role in delayed-phase PGD2 generation is more complex and involves the activation-dependent induction of prostaglandin endoperoxide synthase 2 and the supply of arachidonic acid for metabolism to PGD2.

Bingham, C. O., 3rd, R. J. Fijneman, et al. (1999). "Low molecular weight group IIA and group V phospholipase A(2) enzymes have different intracellular locations in mouse bone marrow-derived mast cells." J Biol Chem 274(44): 31476-84.

The subcellular location of the enzymes of eicosanoid biosynthesis is critical for their co-ordinate action in the generation of leukotrienes and prostaglandins. This activity is thought to occur predominantly at a perinuclear location. Whereas the subcellular locations of cytosolic phospholipase (PL) A(2) and each of the pathway enzymes of eicosanoid generation have been defined, the distribution of the low molecular weight species of PLA(2) has remained elusive because of the lack of antibodies that distinguish among homologous family members. We have prepared affinity-purified rabbit antipeptide IgG antibodies that distinguish mouse group IIA PLA(2) and group V PLA(2). Immunofluorescence staining and immunogold electron microscopy reveal different subcellular locations for the enzymes. Group IIA(2) PLA(2) is present in the secretory granules of mouse bone marrow-derived mast cells, consistent with its putative role in facilitating secretory granule exocytosis and its consequent extracellular action. In contrast, group V PLA(2) is associated with various membranous organelles including the Golgi apparatus, nuclear envelope, and plasma membrane. The perinuclear location of group V PLA(2) is consistent with a putative interaction with translocated cytosolic PLA(2) in supplying arachidonic acid for generation of eicosanoid products, while the location in Golgi cisternae may also reflect its action as a secreted enzyme. The spatial segregation of group IIA PLA(2) and group V PLA(2) implies that these enzymes are not functionally redundant.

Gibbs, B. F., J. P. Arm, et al. (1997). "Human lung mast cells release small amounts of interleukin-4 and tumour necrosis factor-alpha in response to stimulation by anti-IgE and stem cell factor." Eur J Pharmacol 327(1): 73-8.

Recent reports have suggested that mast cells are capable of producing and releasing a number of pro-inflammatory cytokines. However, these studies have mainly been carried out using murine tissue culture derived mast cells and it is known that these cells differ markedly in their functional properties from isolated human mast cells. It was therefore essential to study the release of cytokines from the latter cell type. On immunological stimulation with anti-immunoglobulin E (anti-IgE) or stem cell factor (SCF), purified human lung mast cells released, within 2-10 min, small amounts of tumour necrosis factor-alpha (10.5 +/- 2.9 pg/10(6) mast cells and 17.9 +/- 7.9 pg/10(6) mast cells, respectively) and interleukin-4 (5.3 +/- 2.5 pg/10(6) mast cells and 8.0 +/- 3.2 pg/10(6) mast cells, respectively). After longer periods of activation (30 min-4 h). the amounts of cytokines released from stimulated cells decreased to levels which were below those of the unstimulated cells. This possible degradation of cytokines by mast cells could not be prevented by the addition of protease inhibitors.

Arm, J. P., C. Nwankwo, et al. (1997). "Molecular identification of a novel family of human Ig superfamily members that possess immunoreceptor tyrosine-based inhibition motifs and homology to the mouse gp49B1 inhibitory receptor." J Immunol 159(5): 2342-9.

The co-cross-linking of gp49B1, a member of the Ig superfamily containing immunoreceptor tyrosine-based inhibition motifs, with the high affinity Fc receptor for IgE on mouse bone marrow culture-derived mast cells inhibits IgE-dependent exocytosis and lipid mediator generation. We now describe the cloning of human cDNAs homologous to the mouse gp49 family. A human monocyte cDNA library was probed with the mouse gp49A cDNA, which is 97% identical with mouse gp49B1, to obtain a homologous partial cDNA that was then used to identify and clone full-length cDNAs from monocyte and human lung cDNA libraries. The 1.6-kbp cDNA, HM18, predicts a 49-kDa type 1 integral membrane protein that, like mouse gp49B1, contains two extracellular C2 type Ig superfamily domains and two consensus immunoreceptor tyrosine-based inhibition motifs in the cytoplasmic domain. ALIGN analysis of the amino acid sequence of the extracellular domains showed that HM18 belongs to a family that includes mouse gp49, the bovine Fc receptor for IgG2, the human myeloid Fc receptor for IgA, and the human NK cell inhibitory receptors. The gene encoding HM18, in common with the genes for the human Fc receptor for IgA and the human NK cell inhibitory receptors, was localized to chromosome 19q13.4. Two other closely related cDNAs, each with four C2 Ig superfamily domains, were characterized. Transcripts for these novel Ig superfamily members were identified in peripheral blood monocytes, the THP-1 monocytic cell line, human lung, human lung mast cells, and NK cells. The data suggest that HM18 is a novel mononuclear cell inhibitory receptor homologous to mouse gp49B1.

Penrose, J. F., J. Spector, et al. (1996). "Molecular cloning of the gene for human leukotriene C4 synthase. Organization, nucleotide sequence, and chromosomal localization to 5q35." J Biol Chem 271(19): 11356-61.

Leukotriene C4 (LTC4) synthase catalyzes the conjugation of LTA4 with reduced GSH to form LTC4, the parent of the receptor active cysteinyl leukotrienes implicated in the pathobiology of bronchial asthma. Previous cloning of the cDNA for human LTC4 synthase demonstrated significant homology of its amino acid sequence to that of 5-lipoxygenase activating protein (FLAP) but none to that of the GSH S-transferase super-family. Genomic cloning from a P1 library now reveals that the gene for LTC4 synthase contains five exons (ranging from 71 to 257 nucleotides in length) and four introns, which in total span 2.52 kilobase pairs in length. The intron/exon junctions of LTC4 synthase align identically with those of FLAP; however, the small size of the LTC4 synthase gene contrasts with the > 31-kilobase pair size reported for FLAP. Confirmation of the LTC4 synthase gene size to ensure that no deletions had occurred during the cloning was obtained by two overlapping polymerase chain reactions from genomic DNA, which provided products of the predicted sizes. Primer extension analysis with poly(A)+ RNA from culture-derived human eosinophilic granulocytes or the KG-1 myelogenous cell line revealed multiple transcriptional start sites with prominent signals at 66, 69, and 96 base pairs 5' of the ATG translation start site. The 5'-flanking region revealed a GC-rich promoter sequence consistent with an SP-1 site and consensus sequences for AP-1 and AP-2 enhancer elements, 24, 807, and 877 bp, respectively, 5' from the first transcription initiation site. Southern blot analysis of a genomic DNA (with full-length cDNA as well as 5' and 3' oligonucleotide probes) confirmed the size of the gene and indicated a single copy gene in normal human genomic DNA. Fluorescent in situ hybridization mapped LTC4 synthase to chromosomal location 5q35, which is in close proximity to the cluster of genes for cytokines and receptors involved in the regulation of cells central to allergic inflammation and implicated in bronchial asthma.

Drazen, J. M., J. P. Arm, et al. (1996). "Sorting out the cytokines of asthma." J Exp Med 183(1): 1-5.

Bingham, C. O., 3rd, M. Murakami, et al. (1996). "A heparin-sensitive phospholipase A2 and prostaglandin endoperoxide synthase-2 are functionally linked in the delayed phase of prostaglandin D2 generation in mouse bone marrow-derived mast cells." J Biol Chem 271(42): 25936-44.

BALB/cJ mouse bone marrow-derived mast cells (BMMC) developed with interleukin (IL)-3 can be stimulated by c-kit ligand (KL) in the presence of IL-10 and IL-1beta for sequential immediate and delayed generation of prostaglandin (PG) D2 through utilization of constitutive prostaglandin endoperoxide synthase (PGHS) -1 and induced PGHS-2, respectively (Murakami, M., Matsumoto, R., Austen, K. F., and Arm, J. P. (1994) J. Biol. Chem. 269, 22269-22275). We now report that BALB/cJ BMMC stimulated with KL + IL-10 + IL-1beta also exhibit the biphasic release of [3H]arachidonic acid with an immediate phase over the first 10 min followed by a delayed phase from 2 to 7 h. The delayed phase of arachidonic acid release and of PGD2 generation was inhibited by heparin, which concomitantly released a phospholipase (PL) A2 from the cells into the supernatant. Both dexamethasone and a type II PLA2 inhibitor, 12-epi-scalaradial, suppressed delayed-phase PGD2 generation at concentrations that did not affect immediate eicosanoid generation. Transcripts for type IIA PLA2, as assessed by reverse transcription-polymerase chain reaction, were progressively induced in BALB/cJ BMMC treated for 2 to 7 h with KL + IL-10 + IL-1beta; the induction of these transcripts was down-regulated by 10(-6) M dexamethasone. The expression of steady-state transcripts and protein for cytosolic PLA2 (cPLA2) did not change. PGHS-2-dependent delayed-phase PGD2 generation elicited by IgE-dependent activation of BALB/cJ BMMC primed with KL + IL-10 was also accompanied by the induction of type IIA PLA2 transcripts and was suppressed by heparin, with concomitant release of PLA2 into the supernatant. However, both the direct, cytokine-stimulated and the cytokine-primed, IgE-dependent, delayed-phase PGD2 generation occurred in BMMC from C57BL/6J mice, which have a natural disruption of the type IIA PLA2 gene. Thus, kinetic, pharmacologic, and genetic analyses suggest that an inducible, heparin-sensitive PLA2, rather than cPLA2, provides arachidonic acid to concomitantly induced PGHS-2 for delayed-phase PGD2 biosynthesis in activated BMMC. Furthermore, this heparin-sensitive PLA2 likely represents a novel PLA2 or a new function for a known low molecular weight PLA2.

Murakami, M., C. O. Bingham, 3rd, et al. (1995). "IgE-dependent activation of cytokine-primed mouse cultured mast cells induces a delayed phase of prostaglandin D2 generation via prostaglandin endoperoxide synthase-2." J Immunol 155(9): 4445-53.

Mouse bone marrow-derived mast cells (BMMC) developed with IL-3 generate prostaglandin D2 (PGD2) through the utilization of prostaglandin endoperoxide synthase (PGHS)-1 within several minutes of cross-linking the high affinity Fc receptor for IgE (Fc epsilon RI) by hapten-specific IgE and Ag. We now report that this immediate generation of PGD2 is followed by a 15-fold induction of steady-state transcripts for PGHS-2, with a maximum at 30 min, accompanied by transient expression of PGHS-2 protein. When BMMC were pretreated with c-kit ligand (KL) in combination with IL-10 for 2 h, sensitized with IgE, and activated with Ag, their expression of steady-state transcripts for PGHS-2 increased 111-fold and their expression of PGHS-2 protein was markedly enhanced, with maximal expression at 1 h and 5 h, respectively, after activation. These events were accompanied by PGD2 generation from 1 to 10 h after activation that accounted for approximately 50% of total PGD2 generation. The expression of PGHS-1 protein did not change during this period. The optimal priming interval for the effect of KL plus IL-10 on the IgE-dependent induction of PGHS-2 was 2 h, at which time only this particular cytokine combination acted synergistically with activation by IgE and Ag. In contrast, at 2 days the accessory cytokines that could provide priming with KL included IL-3 and IL-9 in addition to IL-10. Dexamethasone, which inhibited the expression of PGHS-2 but not PGHS-1, and NS-398, a selective inhibitor of PGHS-2, each suppressed the delayed phase but not the immediate phase of PGD2 generation. Conversely, valeryl salicylate, a selective inhibitor of PGHS-1, suppressed the immediate but not the delayed phase of PGD2 generation after cell priming and IgE-dependent activation.

Murakami, M., K. F. Austen, et al. (1995). "Interleukin-3 regulates development of the 5-lipoxygenase/leukotriene C4 synthase pathway in mouse mast cells." J Biol Chem 270(39): 22653-6.

To study cytokine regulation of the 5-lipoxygenase (5-LO)/leukotriene (LT) synthase pathway we have developed mouse bone marrow-derived mast cells (BMMC) that minimally express each protein of the pathway by using a novel culture system, lacking interleukin (IL)-3. When mouse bone marrow cells were cultured for 5 weeks with 100 ng/ml c-kit ligand (KL) and 10 units/ml IL-10, a population of > 95% mast cells was obtained. These cells generated 8.3 +/- 4.5 ng of LTC4/10(6) cells and 8.1 +/- 2.4 ng of prostaglandin (PG) D2/10(6) cells after IgE-dependent activation. When these BMMC were cultured for 2-5 weeks more with 100 units/ml IL-3 in the continued presence of KL and IL-10, the IgE-dependent generation of LTC4 and PGD2 increased to 212 +/- 36 and 25.5 +/- 8.6 ng/10(6) cells, respectively. The dramatic increase in the IgE-dependent generation of LTC4 in response to IL-3 was accompanied by a concomitant increase in expression of 5-LO and 5-LO-activating protein and preceded the increased expression of cytosolic phospholipase A2 and LTC4 synthase. The recognition that IL-3 up-regulates the expression of each protein of the 5-LO pathway for the generation of LTC4 contrasts with our recent finding that KL up-regulates the expression of cytosolic phospholipase A2, prostaglandin endoperoxide synthase-1, and hematopoietic PGD2 synthase and increases the IgE-dependent generation of PGD2 in BMMC developed from bone marrow with IL-3. Thus, developmentally segregated regulation of the prostanoid and cysteinyl leukotriene pathways in lineage-related committed mast cell progenitors reveals the pleiotropism of this effector cell of allergic inflammation, a cytokine/growth factor basis for preferential expression of pathways of eicosanoid biosynthesis, and the particular role of IL-3 in regulating the expression of the proteins of the 5-LO/LTC4 synthase pathway.

Murakami, M., K. F. Austen, et al. (1995). "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." J Exp Med 182(1): 197-206.

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.

Murakami, M., J. F. Penrose, et al. (1995). "Interleukin 4 suppresses c-kit ligand-induced expression of cytosolic phospholipase A2 and prostaglandin endoperoxide synthase 2 and their roles in separate pathways of eicosanoid synthesis in mouse bone marrow-derived mast cells." Proc Natl Acad Sci U S A 92(13): 6107-11.

Mouse bone marrow-derived mast cells (BMMCs) developed with interleukin 3 (IL-3) can be stimulated by c-kit ligand (KL) and accessory cytokines over a period of hours for direct delayed prostaglandin (PG) generation or over a period of days to prime for augmented IgE-dependent PG and leukotriene (LT) production, as previously reported. We now report that IL-4 is counterregulatory for each of these distinct KL-dependent responses. BMMCs cultured for 4 days with KL + IL-3 or with KL + IL-10 produced 5- to 7-fold more PGD2 and approximately 2-fold more LTC4 in response to IgE-dependent activation than BMMCs maintained in IL-3 alone. IL-4 inhibited the priming for increased IgE-dependent PGD2 and LTC4 production to the level obtained by activation of BMMCs maintained in IL-3 alone with an IC50 of approximately 0.2 ng/ml. IL-4 inhibited the KL-induced increase in expression of cytosolic phospholipase A2 (cPLA2) but had no effect on the incremental expression of PG endoperoxide synthase 1 (PGHS-1) and hematopoietic PGD2 synthase or on the continued baseline expression of 5-lipoxygenase, 5-lipoxygenase activating protein, and LTC4 synthase. BMMCs stimulated by KL + IL-10 for 10 h exhibited a delayed phase of PGD2 generation, which was dependent on de novo induction of PGHS-2. IL-4 inhibited the induction of PGHS-2 expression and the accompanying cytokine-initiated delayed PGD2 generation with an IC50 of approximately 6 ng/ml. IL-4 had no effect on the expression of PGHS-2 and the production of PGD2 elicited by addition of IL-1 beta to the combination of KL + IL-10. IL-4 had no effect on the immediate phase of eicosanoid synthesis elicited by KL alone or by IgE and antigen in BMMCs maintained in IL-3. Thus, the counterregulatory action of IL-4 on eicosanoid generation is highly selective for the induced incremental expression of cPLA2 and the de novo expression of PGHS-2, thereby attenuating time-dependent cytokine-regulated responses to stimulation via Fc epsilon receptor I and stimulation via c-kit, respectively.

Murakami, M., R. Matsumoto, et al. (1995). "c-kit ligand mediates increased expression of cytosolic phospholipase A2, prostaglandin endoperoxide synthase-1, and hematopoietic prostaglandin D2 synthase and increased IgE-dependent prostaglandin D2 generation in immature mouse mast cells." J Biol Chem 270(7): 3239-46.

We have examined the cytokine regulation of IgE-dependent prostaglandin (PG) D2 generation in mouse mast cells by assessing the changes in the levels of the transcript, translated protein, and activity of the enzymes involved in the synthesis of PGD2 from endogenous arachidonic acid. When mouse mast cells, derived by culture of bone marrow cells with WEHI-3 cell-conditioned medium as a source of interleukin (IL)-3 (BMMC), were cultured in recombinant ckit ligand (KL), sensitized with IgE, and stimulated with antigen, PGD2 generation increased 3-fold; when KL was combined with IL-3, IL-9, or IL-10, PGD2 generation increased 6-8-fold above that produced by the cells cultured in IL-3 alone. The increased IgE-dependent PGD2 generation by BMMC was apparent after 1 day of culture, reached a maximum after 2-4 days of culture, and was dose-dependent for KL and for each of the accessory cytokines. IgE-dependent generation of leukotriene C4 increased 2-fold after the cells were cultured with KL and was not increased by the addition of IL-3, IL-9, or IL-10. Assays for steady-state transcripts by RNA blotting, for protein by SDS-PAGE/immunoblotting, and for function by enzymatic activities revealed that KL alone stimulated the increased expression of cytosolic phospholipase A2 (cPLA2), prostaglandin endoperoxide synthase (PGHS)-1, and the terminal enzyme, hematopoietic PGD2 synthase, without a change in expression of 5-lipoxygenase. IL-3, IL-9, and IL-10 each enhanced the KL-induced expression of PGHS-1. In contrast, transcripts for PGHS-2, which were detected transiently after the cells had been cultured for 5 h in KL+IL-3, were not expressed during the period of subsequent increase in IgE-dependent PGD2 generation. These findings demonstrate that KL up-regulates expression of cPLA2, PGHS-1, and hematopoietic PGD2 synthase, leading to a relatively selective increase in IgE-dependent production of PGD2 from endogenously released arachidonic acid in BMMC, and they provide the first example of cytokine regulation of hematopoietic PGD2 synthase.

Nasser, S. M., G. S. Bell, et al. (1994). "Effect of the 5-lipoxygenase inhibitor ZD2138 on aspirin-induced asthma." Thorax 49(8): 749-56.

BACKGROUND--The cysteinyl leukotrienes may play a central part in the mechanisms of aspirin-sensitive asthma. Previous work has shown that individuals with aspirin-sensitive asthma have high basal urinary LTE4 levels which increase further upon aspirin ingestion, and that sulphidopeptide leukotriene receptor antagonists attenuate aspirin-induced airflow obstruction. If the cysteinyl leukotrienes cause aspirin-induced asthmatic reactions, inhibition of the 5-lipoxygenase pathway should prevent aspirin-induced bronchospasm. This hypothesis has been tested with ZD2138, a specific non-redox 5-lipoxygenase inhibitor. METHODS--Seven subjects (four men) with aspirin-sensitive asthma with baseline FEV1 values > 67% were studied. ZD2138 (350 mg) or placebo was given on two separate occasions two weeks apart in a randomised double blind fashion. A single dose of aspirin was administered four hours after dosing and FEV1 was measured for six hours. Inhibition of the 5-lipoxygenase pathway by ZD2138 was assessed by measurements of urinary LTE4 levels and ex vivo calcium ionophore stimulated LTB4 generation in whole blood, before administration of drug or placebo and at regular time intervals after dosing and aspirin administration. RESULTS--ZD2138 protected against the aspirin-induced reduction in FEV1 with a 20.3 (4.9)% fall in FEV1 following placebo compared with 4.9 (2.9)% following ZD2138. This was associated with 72% inhibition of ex vivo LTB4 generation in whole blood at 12 hours and a 74% inhibition of the rise in urinary LTE4 excretion at six hours after aspirin ingestion. CONCLUSIONS--In aspirin-sensitive asthma the 5-lipoxygenase inhibitor ZD2138 inhibits the fall in FEV1 induced by aspirin and this is associated with substantial inhibition of 5-lipoxygenase.

Nasser, S. M., G. S. Bell, et al. (1994). "Effect of the 5-lipoxygenase inhibitor ZD2138 on allergen-induced early and late asthmatic responses." Thorax 49(8): 743-8.

BACKGROUND--Leukotrienes are lipid mediators generated from arachidonic acid by the 5-lipoxygenase pathway which may play an important part in the pathophysiology of asthma. Previous studies have demonstrated attenuation of the allergen-induced early and late asthmatic responses by leukotriene receptor antagonists. The effect of the 5-lipoxygenase inhibitor ZD2138, a non-redox lipoxygenase inhibitor which inhibits leukotriene synthesis for 24 hours after single doses of 350 mg, on allergen-induced early and late asthmatic responses has been assessed. METHODS--Eight asthmatic subjects with baseline FEV1 > 70% were studied. On screening, all subjects developed an allergen-induced biphasic asthmatic response to grass pollen, cat dander, or house dust mite. ZD2138 (350 mg) or placebo was given on two occasions separated by two weeks in a randomised double blind fashion. Allergen inhalation challenge was performed four hours after dosing and FEV1 was measured for eight hours. The inhibitory activity of ZD2138 on the 5-lipoxygenase pathway was assessed by measurements of calcium ionophore-stimulated generation of LTB4 in whole blood ex vivo and by analysis of urinary LTE4 levels before administration of drug or placebo and at regular intervals after oral drug dosing and allergen challenge. RESULTS--ZD2138 produced no significant bronchodilatation or attenuation of the early or late asthmatic response, although there was 82% inhibition of whole blood generation of LTB4 in response to calcium ionophore stimulation and 52% reduction in urinary excretion of LTE4. CONCLUSIONS--In asthmatic subjects the 5-lipoxygenase inhibitor ZD2138 did not protect against allergen-induced asthmatic responses, despite substantial inhibition of 5-lipoxygenase.

Murakami, M., J. P. Arm, et al. (1994). "Cytokine regulation of mast cell protease phenotype and arachidonic acid metabolism." Ann N Y Acad Sci 744: 84-98.

Murakami, M., R. Matsumoto, et al. (1994). "Prostaglandin endoperoxide synthase-1 and -2 couple to different transmembrane stimuli to generate prostaglandin D2 in mouse bone marrow-derived mast cells." J Biol Chem 269(35): 22269-75.

The view that the two isoforms of prostaglandin-endoperoxide synthase (cyclooxygenase), PGHS-1 and PGHS-2, mediate physiologic and inflammatory processes, respectively, implies separate pathways of arachidonic acid metabolism with different benefits to the host. Functional segregation of these steps in endogenous arachidonic acid metabolism in a single cell in response to different stimuli is now demonstrated. When mouse bone marrow-derived mast cells developed in interleukin-3 (IL-3)-containing medium were cultured with c-kit ligand in combination with IL-10 and IL-1 beta, transient expression of PGHS-2 mRNA and protein occurred in a dose- and time-dependent fashion, accompanied by substantial release of prostaglandin D2 (PGD2) into the culture medium from 2 to 10 h. In contrast, induction of PGHS-2 did not mediate an increase in PGD2 generation in response to stimulation with IgE and antigen. After a longer period of culture, from 24 to 48 h, the expression of PGHS-1 increased, as did the increase in IgE/antigen-dependent generation of PGD2. Dexamethasone, which inhibited the induction of PGHS-2 but not PGHS-1, and a PGHS-2-selective inhibitor suppressed cytokine-induced PGD2 generation but not IgE-dependent PGD2 generation. Thus, at a time when both PGHS-1 and PGHS-2 are present in bone marrow-derived mast cells, they function independently by coupling to different stimulus-initiated pathways to PGD2 generation from endogenously derived arachidonic acid.

Lane, S. J., J. P. Arm, et al. (1994). "Chemical mutational analysis of the human glucocorticoid receptor cDNA in glucocorticoid-resistant bronchial asthma." Am J Respir Cell Mol Biol 11(1): 42-8.

Corticosteroid-resistant (CR) asthma is not caused by altered bioavailability of the administered drug, altered ligand-binding characteristics, or altered nuclear translocation of the activated human glucocorticoid receptor (hGR) complex. We have tested the hypothesis that CR asthma results from a consistent polymorphism in the functionally diverse hGR cDNA using the sensitive screening technique of polymerase chain reaction (PCR) amplification and chemical mutational analysis. Total RNA was extracted from peripheral blood monocytes derived from six corticosteroid-sensitive (CS) and six CR asthmatic subjects. The RNA was reverse transcribed, and overlapping hGR cDNA fragments were amplified by nested PCR. Double-stranded hGR cDNA fragments were hybridized to corresponding 32P-5'-labeled wild-type fragments, chemically modified with osmium and hydroxylamine, and cleaved with piperidine. The resultant cleaved strands were detected by autoradiography. As controls, single base pair mutated hGR cDNA fragments sensitive to hydroxylamine and osmium modification were used. Using this technique, we did not detect any base pair mismatch between the six CS and six CR patients and the corresponding wild-type hGR, despite a 100% detection of control mutations. We conclude that the defect in CR asthma does not lie in the structure of the hGR.

Hallsworth, M. P., C. P. Soh, et al. (1994). "Selective enhancement of GM-CSF, TNF-alpha, IL-1 beta and IL-8 production by monocytes and macrophages of asthmatic subjects." Eur Respir J 7(6): 1096-102.

Previous work has demonstrated an increase in the production of granulocyte-macrophage colony-stimulating factor (GM-CSF) by monocytes derived from asthmatic individuals. We have suggested that monocytes and macrophages enhance airways inflammation by augmented cytokine production. We tested this hypothesis by measuring the production of GM-CSF and macrophage-derived cytokines, namely interleukin-1 beta (IL-1 beta), tumour necrosis factor-alpha (TNF-alpha) and interleukin-8 (IL-8), from unstimulated and lipopolysaccharide (LPS)-stimulated peripheral blood monocytes and alveolar macrophages in 31 asthmatic and 11 normal, control subjects. The basal production of GM-CSF was four fold higher in the monocytes of asthmatic individuals, but there was no significant difference in the basal production of TNF-alpha, IL-1 beta and IL-8. After stimulation with LPS, asthmatic monocytes produced twofold more GM-CSF and fourfold more IL-1 beta than the monocytes from control subjects. Unstimulated macrophages from asthmatic subjects produced significantly less GM-CSF and TNF-alpha than macrophages from controls, and there was no difference in either IL-1 beta or IL-8 production. When stimulated by LPS, macrophages from asthmatic subjects produced twofold more GM-CSF, threefold more TNF-alpha and fourfold more IL-8. The levels of IL-8 produced by both monocytes and macrophages were at least 20 fold higher than those of the other cytokines measured. There is selectivity in the upregulation of cytokine production by monocytes and macrophages in asthma.(ABSTRACT TRUNCATED AT 250 WORDS)

Castells, M. C., X. Wu, et al. (1994). "Cloning of the gp49B gene of the immunoglobulin superfamily and demonstration that one of its two products is an early-expressed mast cell surface protein originally described as gp49." J Biol Chem 269(11): 8393-401.

gp49 was originally defined as a 49-kDa surface glycoprotein preferentially expressed on mouse interleukin-3-dependent, bone marrow-derived mast cells, which are immature progenitor cells. A previously cloned cDNA (gp49A) indicated that gp49 was a member of the immunoglobulin (Ig) superfamily, and genomic DNA analysis indicated that two genes might encode a gp49 family. We have now characterized a 5.6-kilobase pair gene, gp49B, that encodes two novel gp49 cDNAs, gp49B1 and gp49B2. The two cDNAs are identical except that gp49B2 is missing exon 6, which encodes a predicted transmembrane domain. In contrast to gp49A, gp49B1 and gp49B2 have 32 additional amino acids at their C termini containing 4 of the 6 consensus amino acids of the antigen receptor homology 1 motif found on several signal-transducing members of the Ig superfamily. When COS-7 cells were transfected with either the gp49B1 or gp49B2 cDNA, only the gp49B1 transfectants bound the B23.1 monoclonal antibody that originally defined gp49. Reverse transcriptase-polymerase chain reaction analysis of the transfectants established that both transcripts were expressed, suggesting that the product of the gp49B2 transcript was not inserted in the plasma membrane. Thus, cloning of the gp49B gene has established the organization of one of the gp49 genes and provided evidence of alternate splicing of transcripts from that gene.

Arm, J. P., F. C. Thien, et al. (1994). "Leukotrienes, fish-oil, and asthma." Allergy Proc 15(3): 129-34.

Studies suggest that leukotrienes which have been metabolized from arachidonic acid released from membranes phospholipids during cell activation may play a significant role in a variety of inflammatory disorders including the pathophysiology of chronic allergic asthma. Two major types of polyunsaturated fatty acids prominent in marine fish oils are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DCHA). These fish oils limit leukotriene synthesis and biological activities by substituting substrate fatty acids as alternatives to arachidonic acid. Both EPA and DCHA inhibit the conversion of arachidonic acid by the cyclooxygenase pathway to prostanoid metabolites and reduce the production of platelet-activating factor (PAF).

Arm, J. P. and T. H. Lee (1994). "Evidence for a specific role of leukotriene E4 in asthma and airway hyperresponsiveness." Adv Prostaglandin Thromboxane Leukot Res 22: 227-40.

Lobell, R. B., J. P. Arm, et al. (1993). "Intracellular degradation of Fc gamma RIII in mouse bone marrow culture-derived progenitor mast cells prevents its surface expression and associated function." J Biol Chem 268(2): 1207-12.

Although mouse interleukin-3-dependent, bone marrow culture-derived progenitor mast cells (BMMC) and a Kirsten sarcoma virus (KiSV)-immortalized mouse mast cell line (MC4w) both express on their surfaces receptors for the Fc portion of IgG (Fc gamma R), only MC4w degranulate upon Fc gamma R perturbation. As shown by surface iodination and SDS-polyacrylamide gel electrophoresis analysis of deglycosylated proteins immunoprecipitated with the Fc gamma R-specific monoclonal antibody 2.4G2, a 26-kDa protein, identified as Fc gamma RIII by immunoblotting with antibody to Fc gamma RIII, was predominantly expressed on the surface of MC4w but minimally on BMMC. However, both BMMC and MC4w expressed mRNA for Fc gamma RIII as determined by RNA blot analysis, and both translated Fc gamma RIII as assessed by intrinsic radiolabeling and SDS-polyacrylamide gel electrophoresis analysis of deglycosylated monoclonal antibody 2.4G2 immunoprecipitates. Pulse-chase analysis showed that intrinsically radiolabeled Fc gamma RIII was stable in MC4w cells but was degraded rapidly in BMMC and that newly synthesized Fc gamma RIII remained sensitive to digestion by endoglycosidase H in BMMC but rapidly became resistant in MC4w. These data suggest that the deficiency in surface Fc gamma RIII expression on BMMC is due to the degradation of Fc gamma RIII in the endoplasmic reticulum. Immunoprecipitation of surface Fc gamma R and Fc receptors for IgE (Fc epsilon RI) from digitonin-extracted cells followed by immunoblotting with antibody to Fc epsilon RI gamma-chain showed that gamma-chain is associated with surface Fc epsilon RI and Fc gamma R in MC4w, but only with Fc epsilon RI in BMMC, which lack surface Fc gamma RIII. Inasmuch as BMMC are progenitors of serosal mast cells, which, like MC4w, express surface Fc gamma RIII and undergo Fc gamma R-mediated activation, the data suggest that maturation of BMMC enables Fc gamma RIII to bypass degradation in the endoplasmic reticulum, resulting in the acquisition of functional Fc gamma RIII/gamma-chain complexes on the cell surface.