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T C Theoharides

Publications and source records attributed to T C Theoharides.

At least 91 records · Page 5Linked to original sources
PubMed1993

Quercetin-induced expression of rat mast cell protease II and accumulation of secretory granules in rat basophilic leukemia cells.

Rat basophilic leukemia (RBL) cells are considered to be similar to bone-marrow derived mast cells and to mucosal mast cells (MMC), the latter of which may be involved in inflammatory bowel diseases. RBL cells are not able to accumulate histamine and secretory granules under regular growing conditions. Here we show that the flavonoid quercetin, which inhibits mast cell secretion of histamine, also inhibited RBL cell proliferation and constitutive histamine release while it induced synthesis of rat mast cell protease (RMCP) II and triggered processes leading to accumulation of secretory granules. Cell viability was also retained in the presence of quercetin, whereas untreated cells did not survive past 6 days of growth. Quercetin did not affect the expression of mRNA for alpha-subunit of immunoglobulin E (IgE) receptor, but led to increased expression of mRNA for, and synthesis of RMCP II, which is a marker protein for MMC. Many of these granules showed metachromasia with toluidine blue after 3 days of growth, stained red with alcian blue counterstained with safranin after 8 days of growth, and contained electron dense material. Our results suggest that RBL cells have the capacity to progress to a more mature state and may lend themselves to further analysis of a growth regulator(s) with action similar to that of quercetin.

Animals↗
PubMed1993

Synergistic action of estradiol and myelin basic protein on mast cell secretion and brain myelin changes resembling early stages of demyelination.

Mast cells are known for their participation in immediate and, more recently, delayed hypersensitivity reactions. They have been found in the meninges and certain brain areas where they are strictly perivascular, in close apposition to neurons, and they are activated by direct nerve stimulation or by neuropeptides. Intracranial mast cells contain many vasoactive substances which can increase the permeability of the blood-brain barrier, proteolytic enzymes which can degrade myelin in vitro, as well as chemotactic molecules which can attract inflammatory molecules in vivo. Connective tissue mast cells, with which intracranial mast cells share many characteristics, contain cytokines which can cause inflammation directly. Multiple sclerosis is a human demyelinating disease of unknown etiology, with a high prevalence in women which results in penetration of blood-borne immune cells within the brain parenchyma and subsequent destruction of myelin. Here, we report that 17 beta-estradiol and myelin basic protein, a major suspected immunogen in multiple sclerosis, had a synergistic action on inducing mast cell secretion. This effect was more pronounced in Lewis rats, which are susceptible to the development of experimental allergic encephalomyelitis, an animal model for multiple sclerosis, than in Sprague-Dawley rats, which are fairly resistant. Moreover, 18 h incubation of purified peritoneal mast cells with homogeneic slices of brain white matter in the presence of 17 beta-estradiol and myelin basic protein resulted in myelin changes resembling early stages of brain demyelination, which were also more evident in Lewis rats than in Sprague-Dawley rats. These results support the notion that mast cells could participate in the pathophysiology of demyelinating diseases.

Animals↗
PubMed1993

Dermatitis characterized by mastocytosis at immunization sites in mast-cell-deficient W/Wv mice.

W/Wv mice have been extensively used as an important model to study the maturation/differentiation and pathophysiology of mast cells. These albino mice have been shown to have less than 1% of the mast cells found in the skin of their +/+ controls or other normal mice. Moreover, no mast cells are detected in other organs even though they apparently have an adequate number of mast cell precursors. Presumably, these precursors do not respond appropriately to microenvironmental growth factors, while 'normal' precursors from the +/+ controls of S1/S1d-deficient mice mature appropriately in the tissue microenvironment of the W/Wv mice. Female W/Wv mice and +/+ controls were immunized with allogeneic spinal cord homogenate in complete Freund's adjuvant and Mycobacterium tuberculosis in order to induce experimental allergic encephalomyelitis. All W/Wv mice developed extensive dermatitis with mastocytosis at the injection sites about 4 months after inoculation. Mast cells were identified by light microscopy following staining with toluidine blue and berberine sulfate as well as electron microscopy. They were also found to be functional since they secreted serotonin and histamine in response to either compound 48/80 or carbachol. The majority of these mast cells were, therefore, considered to be mature, connective tissue like, but many of them were in different stages of granule maturation as seen with electron microscopy. These findings imply that W/Wv mice may not always be appropriate as models of mast cell deficiency. Moreover, these results suggest that the 'defect' in W/Wv mast cell precursors can be overcome by factors produced during immunization and/or development of dermatitis. These findings may, therefore, help elucidate what regulates mast cell maturation/differentiation as well as their pathophysiology.

Animals↗
PubMed1992

5-Hydroxytryptamine receptor agonists for the abortive treatment of vascular headaches block mast cell, endothelial and platelet activation within the rat dura mater after trigeminal stimulation.

Antidromic stimulation of small caliber trigeminal axons causes neurogenic inflammation in the dura mater and tongue as evidenced by marked increases in mast cell activation, protein extravasation, as well as in the numbers of endothelial cytoplasmic vesicles, endothelial microvilli and platelet aggregates within ipsilateral post-capillary venules. In this report, we examined the effects of pretreatment with serotonin1 receptor agonists, dihydroergotamine (50 micrograms/kg, i.v.) and sumatriptan (100 micrograms/kg, i.v.) on the light and electron microscopic changes which develop after trigeminal ganglion stimulation. Both dihydroergotamine and sumatriptan are useful in the acute treatment of vascular headaches and bind with high affinity to 5-HT1D receptors. Both drugs decreased significantly the number of dural vessels showing endothelial or platelet changes and the numbers of activated mast cells, but did not affect the neurogenic response in the tongue. The drugs also blocked the accumulation of horseradish peroxidase reaction product within the endothelium and perivascular space on the stimulated side. The receptor is not present on trigeminovascular fibers innervating extracranial cephalic tissues. Drug mechanism probably involves inhibition of a proximal step in the pathophysiological cascade (e.g., via activation of a prejunctional receptor) because (a) receptors for sumatriptan have not been identified on mast cells whereas the inflammatory response was attenuated in mast cells as well as within platelets and the endothelium and (b) previous work indicates that sumatriptan and dihydroergotamine block neurotransmitter release. Hence, constriction of vascular smooth muscle mediated by postjunctional 5-hydroxytryptamine receptors is unlikely to explain the anti-inflammatory actions of dihydroergotamine or sumatriptan reported here.

Animals↗
PubMed1992

Inhibition of mast cell secretion by oxidation products of natural polyamines.

Mast cells secrete many biologically active compounds upon stimulation by immunoglobulin E (IgE) and specific antigen (Ag), anaphylatoxins, as well as a number of cationic compounds which include drugs, kinins and neuropeptides. The effects of the two naturally occurring polyamines, spermine (SP) and spermidine (SPD), on mast cell secretion were studied because they have been implicated in the modulation of cellular processes, possibly through their cationic charge or the regulation of calcium ions. SP and SPD over the range of 10(-7) to 10(-4) M inhibited the release of 5-hydroxytryptamine (5-HT, serotonin) triggered by compound 48/80 (C48/80) in a time- and concentration-dependent manner, as long as at least 2% calf serum (CS) was present. SP also inhibited secretion of both histamine and serotonin stimulated immunologically by using IgE and anti-rat IgE. This inhibition was not accompanied by cytotoxicity. The major available polyamine metabolites tested, N1-acetyl spermine (N1-acSP) and N8-acetyl spermidine (N8-acSPD), also showed inhibition in the presence of CS, whereas putrescine, N8,N1-hexamethylene-bis-acetamide (HMBA) and benzylamine did not. Fetal bovine serum (FBS), as well as human and rat serum, which do not contain polyamine oxidase, did not result in any inhibition with the polyamines tested. Inhibitors of the polyamine oxidase blocked the polyamine effect, indicating that the inhibition of mast cell secretion must derive from aldehydes produced from these polyamines. Addition of the aldehyde inhibitor phenylhydrazine (phi-HDZ), simultaneously with, but not following the polyamines, blocked their inhibitory effect, further strengthening the involvement of aldehydes. These results indicate that naturally occurring polyamines may regulate mast cell secretion through metabolic products of polyamine oxidase, a similar enzyme of which is also present in human liver, placenta and pregnant serum.

Animals↗
PubMed1992

Role of lipoxins A4 and B4 in the generation of arachidonic acid metabolites by rat mast cells and their effect on [3H]serotonin release.

Basophils located in tissues are called mast cells and are found in connective tissue. Many different compounds are secreted from basophil granules upon appropriate stimulation. Products such as heparin, histamine, serotonin (5-hydroxytryptamine, 5-HT), and membrane-derived materials which give rise to arachidonic acid metabolites, such as prostaglandins and leukotrienes, are some of the more important compounds released by mast cells. These compounds, when released after stimulation with a variety of molecules, such as IgE, specific antigen anaphylotoxin, as well as the compound 48/80 (C48/80) or calcium ionophore A23187, cause contraction of endothelial cells and mediate atopic or anaphylactic hypersensitivity. In this report, we study the generation of some arachidonic acid products, namely leukotrienes C4, D4, E4, and B4 and the prostaglandins D2 and E2 by rat peritoneal mast cells (RPMC), using calcium ionophore A23187 as a degranulating agonist. We have also studied the new lipoxygenase products, lipoxins A4 and B4, on RPMC secretion using C48/80 as a secretagogue. A rat basophilic leukemia cell line (RBL) was also used to compare results with RPMC. In this paper we have demonstrated that RPMC stimulated with A23187 release LTC4, LTD4, LTE4 and LTB4 and also PGD2 but not PGE2. These results were also confirmed when RBLs were used. In addition, we have shown that mast cells pretreated with LTC4, LTD4, LTE4 or 15-HETE do not modify the release of [3H]5HT exerted by C48/80 (0.5 microgram/ml) or A23187 (5 micrograms/ml). When LXA4 or B4 was used, mast cells were inhibited slightly (not statistically significant) from degranulating after the secretagogue treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Ultrastructural evidence for neurogenically mediated changes in blood vessels of the rat dura mater and tongue following antidromic trigeminal stimulation.

We investigated the effects of unilateral electrical trigeminal ganglion stimulation (0.1 or 1.0 mA, 5 Hz, 5 ms, 5 min) on the morphology of blood vessels within the rat dura mater and tongue using light and transmission electron microscopy. Stimulation at both intensities caused changes which were confined to the ipsilateral post-capillary venules except in the tongue where arterioles were affected as well. Changes were more marked after 1.0 mA. Dramatic increases in the numbers of endothelial pinocytotic vesicles were found along the luminal and abluminal surfaces ipsilateral to the stimulation. Tight junctions remained largely intact, except that injected ferritin particles were occasionally trapped inside these junctions. Cytoplasmic microvilli and endothelial blebs were sometimes present as well. Approximately 80% of the examined dural post-capillary venules showed one or more of these endothelial changes. Horseradish peroxidase injected intravenously 5 min prior to stimulation was detected in the extracellular space surrounding dural blood vessels and within pinocytotic vesicles. Ferritin injected similarly, was also localized in post-capillary venule walls, interstitial spaces, intraendothelial vesicles and in vacuoles. Platelet accumulation and aggregation were present in approximately 10% of post-capillary venules in dura and tongue. These changes were associated with mast cell secretion, but neither vascular nor mast cell activation was observed in adult rats in whom C-fibers were destroyed during the neonatal period with capsaicin. The present observations provide morphological evidence which supports findings from previously reported albumin tracer studies suggesting enhanced transport and endothelial activation following electrical stimulation of small caliber afferent fibers.

Animals↗
PubMed1992

Estradiol augments while tamoxifen inhibits rat mast cell secretion.

Mast cells have been studied extensively for their involvement in allergic reactions, where they secrete numerous powerful mediators in response to immunoglobulin E and specific antigens. However, they are also triggered by neuropeptides, they have been found in close contact with neurons, and they are activated in diseases such as angioedema, interstitial cystitis and irritable bowel disease, the prevalence of which is much higher in women. When tested on purified rat peritoneal mast cells, 17 beta-estradiol augmented secretion of histamine and serotonin, starting at 1 microM and in a dose-dependent manner, whether stimulated by the mast cell secretagogue compound 48/80 or the neuropeptide substance P. However, 17 beta-estradiol did not augment mast cell secretion stimulated by immunoglobulin E and specific antiserum indicating that immunologic stimulation is under different regulation. Testosterone inhibited secretion induced by compound 48/80. Tamoxifen, an estrogen receptor antagonist used in the treatment of breast cancer, inhibited serotonin and histamine release from purified rat peritoneal mast cells triggered by compound 48/80 or substance P. Tamoxifen also inhibited the increase in intracellular free Ca2+ originating from an influx of extracellular Ca2+ in response to compound 48/80. Moreover, tamoxifen antagonized the synergistic effect of phorbol myristate and the cation ionophore A23187 on mast cell secretion, suggesting that tamoxifen's inhibition may be due to regulation of protein kinase C activity. Tamoxifen may, therefore, have a beneficial effect in other neuroimmunoendocrine disorders both through estrogen receptor blockade and inhibition of mast cell secretion.

Animals↗
PubMed1992

Activation of bladder mast cells in interstitial cystitis.

Interstitial cystitis (IC) is a sterile, inflammatory bladder condition characterized by urinary frequency and urgency, as well as burning and suprapubic pain, which occurs more frequently in women who may suffer for years before diagnosis. An increased number of mast cells have been associated with IC, but the published reports are inconclusive and often conflicting. Human bladder biopsies were analysed blindly for the degree of activation of mast cells in control and IC patients. It was found that mast cells from IC patients averaged as high as 34 cells/mm2 as compared to less than 16/mm2 in controls. Electron microscopy revealed that over 90% of mast cells from IC patients were activated to various degrees. It is concluded that mast cell activation is a pathologic characteristic for IC.

Cystitis↗
PubMed1991

Two-dimensional gel electrophoretic profile of rat basophilic leukemia (RBL) and mast cells.

RBL cells are not differentiated, but resemble mucosal mast cells (MMC). Two-dimensional (2-D) gel electrophoresis following isoelectric focusing (IEF) was performed using purified rat peritoneal mast cells and RBL cells. Certain similarities were identified with silver staining between mast cells and stationary phase (72 hr) RBL cells. RBL cells were also labelled with [35S]-cysteine in order to study the specific expression of proteins during logarithmic or stationary growth phases. Only stationary phase RBL cells appeared to specifically express three proteins of 42, 55 and 93 kD and were still capable of secreting histamine in response to immunoglobulin E (IgE) and specific antigen. These results suggest that specific RBL cell proteins may be used as markers for further analysis of their maturation/differentiation.

Animals↗
PubMed1991

Trigeminal sensory fiber stimulation induces morphological changes reflecting secretion in rat dura mater mast cells.

Mast cells are involved in allergic reactions, but may also participate in neurogenic inflammation. The morphology of mast cells in rat dura mater and tongue was evaluated by histochemistry, as well as by scanning and transmission electron microscopy following unilateral trigeminal ganglion stimulation (5 min, 5 Hz, 5 ms, and 0.02, 0.1 or 1.0 mA). Mast cells in dura and tongue of normal animals were numerous, perivascular and often in close proximity to nerve fibers. After 5 min of electrical stimulation, mast cells contralateral to the stimulation showed histochemical characteristics of normal peripheral tissue mast cells (Safranin-positive), and by electron microscopy appeared homogeneous with numerous intact electron-dense granules. On the stimulated side, however, the staining characteristics of mast cells showed changes indicating progressive intracellular loss of their granular content. In addition, the total number of stainable mast cells decreased at all three stimulus intensities, but reached significance only at 0.1 and 0.02 mA. Ultrastructural evidence of granule changes consistent with secretion were observed although degranulation was not observed until 20 min after stimulation. There were no mast cell changes after electrical trigeminal stimulation in adult rats treated as neonates with capsaicin to destroy small caliber sensory afferent axons. These results suggest that mast cells may secrete in response to electrical stimulation of trigeminal axons, possibly mediated by antidromic release of neuropeptides, and may participate in the development of neurogenic inflammation.

Animals↗
PubMed1991

Endogenous regulation of rat brain mast cell serotonin release.

Mast cells are involved in allergic reactions where they release numerous vasoactive and other mediators in response to IgE and antigen. They are also activated by neuropeptides and are found in close contact with neurons. Mast cell heterogeneity has now been documented for mucosal mast cells and connective tissue mast cells. Rat brain mast cells were studied in a perfusion system and were shown to release serotonin in response to the mast cell secretagogue compound 48/80 (C48/80). High-potassium neuronal depolarization also released serotonin, but this was calcium dependent, not associated with beta-hexosaminidase, and was unaffected by prior treatment with C48/80. Neuronal depolarization, however, was associated with somatostatin secretion and substantially reduced subsequent C48/80 stimulation, an effect abolished by neonatal treatment of the animals with capsaicin. Perfusion with somatostatin and substance P also induced brain mast cell serotonin release. C48/80 stimulation of combined thalamic and hypothalamic slices after neuronal depolarization substantially reduced the C48/80 effect, suggesting the possible presence of endogenous inhibitors released from the hypothalamus. Finally, the alpha 2-receptor agonist clonidine had a slight stimulatory effect. These results indicate that brain mast cell serotonin release may be regulated by endogenous neurotransmitters and/or neuromodulators.

Animals↗
PubMed1991

Characterization of rabbit ileal receptors for Clostridium difficile toxin A. Evidence for a receptor-coupled G protein.

The purpose of this study was to characterize the surface receptor for toxin A, the enterotoxin from Clostridium difficile, on rabbit intestinal brush borders (BB) and on rat basophilic leukemia (RBL) cells. Purified toxin A was radiolabeled using a modified Bolton-Hunter method to sp act 2 microCi/micrograms, with retention of full biologic activity. 3H-Toxin A bound specifically to a single class of receptors on rabbit BB and on RBL cells with dissociation constants of 5.4 x 10(-8) and 3.5 x 10(-8) M, respectively. RBL cells were highly sensitive to toxin A (cell rounding) and had 180,000 specific binding sites per cell, whereas IMR-90 fibroblasts were far less sensitive to toxin A and lacked detectable specific binding sites. Exposure of BB to trypsin or chymotrypsin significantly reduced 3H-toxin A specific binding. Preincubation of BB with Bandeirea simplicifolia (BS-1) lectin also reduced specific binding, and CHAPS-solubilized receptors could be immobilized with WGA-agarose. The addition of 100 nM toxin A accelerated the association of 35S-GTP gamma S with rabbit ileal BB, and preincubation of BB with the GTP analogues GTP gamma S or Gpp(NH)p, significantly reduced 3H-toxin A specific binding. Our data indicate that the membrane receptor for toxin A is a galactose and N-acetyl-glucosamine-containing glycoprotein which appears to be coupled to a G protein.

Animals↗
PubMed1991

Bladder mast cell activation in interstitial cystitis.

The bladder mast cell contains many granules, each one of which can secrete many vasoactive and nociceptive molecules. A number of conditions such as extreme cold, drugs, neuropeptides, stress, trauma, toxins, etcetera, can trigger the mast cell to secrete some of its contents. In turn, these chemicals can sensitize sensory neurons, which can further activate mast cells by releasing neurotransmitters or neuropeptides. Additionally, the mast cell can directly cause vasodilation and bladder mucosa damage while attracting inflammatory cells, thus causing many of the problems observed in IC. Clinicians may be at a distinct disadvantage because they are faced with a multitude of potential mast cell triggers and numerous mediators secreted. Therefore, it may be advisable to block or inhibit the mast cell from responding to many of these various stimuli. Specific mast cell mediators should be assayed as possible diagnostic tools, whereas potential inhibitors of mast cell secretion should be tried under controlled conditions to determine the extent of therapeutic benefit.

Animals↗
PubMed1990

Migration of mast cells in the developing rat brain.

Mast cells are known to derive from the bone marrow and enter the tissues as immature cells which differentiate under local microenvironmental factors. However, it has not been known how and when these cells enter the brain; moreover, the localization of mast cells in the developing rat brain differs from that of the adult animal. Our anatomical and morphological observations showed that during late embryonic stages and the first 11 days after birth, rat brain mast cells were exclusively concentrated within the pia mater surrounding the diencephalon, the choroid fissure and within the choroid plexus. Histochemically these cells contained only a few toluidine blue metachromatic granules, suggesting a 'mucosal' phenotype and the absence of heparin. Later, during a transitional phase from postnatal day 11 to 13, these cells migrated along blood vessels of the fimbria, the hippocampus and the penetrating vessels of the thalamus into the dorsolateral and posterolateral thalamic nuclei. These cells contained more metachromatic granules, and from day 13 on, they assumed their adult perivascular localization within the thalamus with numerous metachromatic granules similar to those described for mature thalamic and serosal mast cells.

Aging↗
PubMed1990

Ultrastructural characteristics of rat peritoneal mast cells undergoing differential release of serotonin without histamine and without degranulation.

Rat mast cells pretreated with the tricyclic antidepressant drug amitriptyline and stimulated with compound 48/80 secreted 60% of the total serotonin present in the cells, but only 15% of histamine, another amine stored in the same granules. Ultrastructural studies demonstrated that mast cells undergoing such differential release do not exhibit classical degranulation by compound sequential exocytosis. However, there were changes in granule shape and size, as well as alterations in many morphometric parameters consistent with secretion. Storage granules lost their homogeneity, exhibited greatly reorganized matrix and were surrounded by clear spaces which were often associated with small (0.1-0.01 microns) cytoplasmic vesicles, some of which contained electron-dense material. Secretory granules often had bud-like protrusions or were fused together in series. Quantitative autoradiography localized 3H-serotonin outside the storage granules, close to small vesicles, while staining with ruthenium red demonstrated that vesicular structures associated with differential release were not endocytotic. These results suggest that amitriptyline may inhibit regular exocytosis and permit at least serotonin to be moved selectively from storage granules to the cytosol or small vesicles from which it is eventually released.

Amitriptyline↗
PubMed1990

Mast cells: the immune gate to the brain.

Mast cells were originally considered wandering histiocytes, but are now known to derive from the bone marrow and enter the tissues as immature or precursor cells which then differentiate under micro-environmental influences such as interleukin-3. At least three types of mature mast cells have been identified as serosal (lung, peritoneal, skin), mucosal (nasal, gastrointestinal) and brain (dural, perivascular, parenchymal) with their own distinct biochemical, morphological and functional characteristics. Mast cells are necessary for immediate hypersensitivity reactions where they release numerous biologically powerful mediators in response to immunoglobulin E (IgE) and antigen (Ag), and appear to be required for delayed reactions. Anaphylatoxins, basic peptides and drugs, as well as certain neuropeptides and hormones, can also trigger mast cell secretion. Recent evidence indicates that mast cells are found in close proximity to neurons, an association which may be regulated by nerve growth factor. Moreover, mast cells may be capable of selective release of mediators which could, in turn, regulate further secretion. This information suggests that mast cells may serve as a link between the immune, endocrine and nervous systems and could have an important role in the access of lymphocytes and pathogens to the brain. The possible role of such interactions in the pathophysiology of specific neuroinflammatory conditions is also discussed.

Animals↗