Histamine release induced by dynorphin-(1-13) from rat mast cells

MRGPRX2 activation as a rapid, high-throughput mechanistic-based approach for detecting peptide-mediated human mast cell degranulation liabilities

Mast cells play key roles in allergy, anaphylaxis/anaphylactoid reactions, and defense against pathogens/toxins. These cells contain cytoplasmic granules with a wide spectrum of pleotropic mediators that are released upon activation. While mast cell degranulation (MCD) occurs upon clustering of the IgE receptor bound to IgE and antigen, MCD is also triggered through non-IgE-mediated mechanisms, one of which is via Mas-related G protein-coupled receptor X2 (MRGPRX2). MRGPRX2 can be activated by many basic biogenic amines and peptides. Consequently, MRGPRX2-mediated MCD is an important potential safety liability for peptide therapeutics. To facilitate peptide screening for this liability in early preclinical drug development, a rapid, high-throughput engineered CHO-K1 cell-based MRGPRX2 activation assay was evaluated and compared to histamine release in CD34⁺ stem cell-derived mature human mast cells as a reference assay, using 30 positive control and 29 negative control peptides for MCD. Both G protein-dependent (Ca²⁺ endpoint) and -independent (β-arrestin endpoint) pathways were assessed in the MRGPRX2 activation assay. The MRGPRX2 activation assay had a sensitivity of 100% for both Ca²⁺ and β-arrestin endpoints and a specificity of 93% (β-arrestin endpoint) and 83% (Ca²⁺ endpoint) compared to histamine release in CD34⁺ stem cell-derived mature human mast cells. These findings suggest that assessing MRGPRX2 activation in an engineered cell model can provide value as a rapid, high-throughput, economical mechanism-based screening tool for early MCD hazard identification during preclinical safety evaluation of peptide-based therapeutics.

Evidence for the modulation of nociception in mice by central mast cells

BACKGROUND

Hyperalgesia that develops following nerve ligation corresponds temporally and in magnitude with the number of thalamic mast cells located contralateral to the ligature. We tested the possibility that mast cells modulate nociception centrally, similar to their role in the periphery.

METHODS

We examined the central effect of two hyperalgesic compounds that induce mast cell degranulation and of stabilized mast cells using cromolyn.

RESULTS

Thermal hyperalgesia (tail flick) induced by nerve growth factor (NGF, a neurotrophic compound) and mechanical hyperalgesia (von Frey) induced by dynorphin A (1-17) (opioid compound) each correlated with the per cent of thalamic mast cells that were degranulated. Degranulation of these mast cells by the central injection of compound 48/80, devoid of neurotrophic or opioid activity, was sufficient to recapitulate thermal hyperalgesia. Stabilization of mast cells by central injections of cromolyn produced no analgesic effect on baseline tail flick or von Frey fibre sensitivity, but inhibited thermal hyperalgesia produced by compound 48/80 and tactile hyperalgesia induced by dynorphin and by Freund's complete adjuvant. Finally, chemical nociception produced by the direct activation of nociceptors by formalin (phase I) was not inhibited by centrally injected cromolyn whereas chemical nociception dependent on central sensitization (formalin-phase II and acetic acid-induced abdominal stretches) was.

CONCLUSIONS

These convergent lines of evidence suggest that degranulation of centrally located mast cells sensitizes central nociceptive pathways leading to hyperalgesia and tonic chemical sensitivity.

SIGNIFICANCE

Hyperalgesia induced by spinal nerve ligation corresponds temporally and in magnitude with degranulation of thalamic mast cells. Here, we provide evidence that hyperalgesia induced by NGF, formalin and dynorphin also may depend on mast cell degranulation in the CNS whereas cromolyn, a mast cell stabilizer, blocks these effects in mice.

The opioid peptide dynorphin A induces leukocyte responses via integrin Mac-1 (αMβ2, CD11b/CD18)

Background

Opioid peptides, including dynorphin A, besides their analgesic action in the nervous system, exert a broad spectrum of effects on cells of the immune system, including leukocyte migration, degranulation and cytokine production. The mechanisms whereby opioid peptides induce leukocyte responses are poorly understood. The integrin Mac-1 (α_Mβ₂, CD11b/CD18) is a multiligand receptor which mediates numerous reactions of neutrophils and monocyte/macrophages during the immune-inflammatory response. Our recent elucidation of the ligand recognition specificity of Mac-1 suggested that dynorphin A and dynorphin B contain Mac-1 recognition motifs and can potentially interact with this receptor.

Results

In this study, we have synthesized the peptide library spanning the sequence of dynorphin AB, containing dynorphin A and B, and showed that the peptides bound recombinant α_MI-domain, the ligand binding region of Mac-1. In addition, immobilized dynorphins A and B supported adhesion of the Mac-1-expressing cells. In binding to dynorphins A and B, Mac-1 cooperated with cell surface proteoglycans since both anti-Mac-1 function-blocking reagents and heparin were required to block adhesion. Further focusing on dynorphin A, we showed that its interaction with the α_MI-domain was activation independent as both the α7 helix-truncated (active conformation) and helix-extended (nonactive conformation) α_MI-domains efficiently bound dynorphin A. Dynorphin A induced a potent migratory response of Mac-1-expressing, but not Mac-1-deficient leukocytes, and enhanced Mac-1-mediated phagocytosis of latex beads by murine IC-21 macrophages.

Conclusions

Together, the results identify dynorphins A and B as novel ligands for Mac-1 and suggest a role for the Dynorphin A-Mac-1 interactions in the induction of nonopiod receptor-dependent effects in leukocytes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12990-015-0027-0) contains supplementary material, which is available to authorized users.

Translocation of Dynorphin Neuropeptides across the Plasma Membrane

Several peptides, including penetratin and Tat, are known to translocate across the plasma membrane. Dynorphin opioid peptides are similar to cell-penetrating peptides in a high content of basic and hydrophobic amino acid residues. We demonstrate that dynorphin A and big dynorphin, consisting of dynorphins A and B, can penetrate into neurons and non-neuronal cells using confocal fluorescence microscopy/immunolabeling. The peptide distribution was characterized by cytoplasmic labeling with minimal signal in the cell nucleus and on the plasma membrane. Translocated peptides were associated with the endoplasmic reticulum but not with the Golgi apparatus or clathrin-coated endocytotic vesicles. Rapid entry of dynorphin A into the cytoplasm of live cells was revealed by fluorescence correlation spectroscopy. The translocation potential of dynorphin A was comparable with that of transportan-10, a prototypical cell-penetrating peptide. A central big dynorphin fragment, which retains all basic amino acids, and dynorphin B did not enter the cells. The latter two peptides interacted with negatively charged phospholipid vesicles similarly to big dynorphin and dynorphin A, suggesting that interactions of these peptides with phospholipids in the plasma membrane are not impaired. Translocation was not mediated via opioid receptors. The potential of dynorphins to penetrate into cells correlates with their ability to induce non-opioid effects in animals. Translocation across the plasma membrane may represent a previously unknown mechanism by which dynorphins can signal information to the cell interior.

Unilateral spinal nerve ligation leads to an asymmetrical distribution of mast cells in the thalamus of female but not male mice

Mast cells are restricted to the leptomeninges and thalamus of healthy mice. These populations are increased by stress and highly sensitive to reproductive hormones. To examine the influence of nociception, a form of stress, on thalamic mast cells, we ligated the left fifth lumbar spinal nerve of male and female mice to induce hyperalgesia. Two, 7 and 14 days later, mice were killed and thalami examined histologically using toluidine blue stain. The total number of thalamic mast cells was not influenced by ligation of the spinal nerve compared to sham-operation in either female or male mice. However, in females, the percent of thalamic mast cells located on the side of the thalamus contralateral to the ligation was greater on days 2 and 7, coincident with mechanical hyperalgesia. At these times, areas in which mast cells were most dense contralateral to nerve-injury included the posterior (Po) and lateral geniculate (LG) nuclei compared to their symmetrical distribution in sham-operated mice. These data suggest that local nociceptive signals to each side of the thalamus rather than stress hormones influence the location of mast cells during the development of allodynia and hyperalgesia. In addition, both hyperalgesia and mast cell distribution induced by nerve-ligation differ in females compared to males, reflecting a novel neuroimmune response to pain within the CNS.

Enhancement of phagocytosis by dynorphin A in mouse peritoneal macrophages

The effects of the opioid peptide dynorphin A (DynA) on phagocytosis in peritoneal macrophages was examined by flow cytometry (FCM). DynA enhanced phagocytosis in a dose-dependent manner. Leucine-enkephalin (Leu-Enk), methionine-enkephalin (Met-Enk), beta-neo-endorphin (beta Neo-End), DynA(9-17) and DynA(13-17) had no such activity. Alpha-Neo-endorphin (alpha Neo-End), dynorphin B (DynB), DynA(1-13) and DynA(6-17) enhanced phagocytosis less effectively than DynA. Naloxone did not inhibit the enhancement of phagocytosis induced by DynA. Unstimulated control phagocytosis was partially suppressed in Ca2+-free EGTA-containing solution and even in this solution DynA enhanced phagocytosis. However, the enhancement by DynA was suppressed in EGTA- and BAPTA-AM-containing Ca2+-free solution. The present study showed that enhancement of phagocytosis by DynA was independent of extracellular Ca2+ ([Ca2+]o) and dependent on intracellular Ca2+ ([Ca2+]i). The present results support DynA being one of the mediators from the nervous system that modulates the immune system.

Dynorphin, a preferential ligand for κ-opioid receptors, is present in nerve fibers and immune cells within inflamed tissue of the rat

Exogenous kappa-opioid agonists have been shown to produce peripheral antinociceptive effects in inflamed tissue. This study sought to determine whether endogenous kappa-receptor ligands are present at the site of inflammation. In Freund's adjuvant-induced hindpaw inflammation in the rat, we show, by immunohistochemistry, that dynorphin is detectable within inflammatory cells and in the cutaneous nerves in a similar distribution as calcitonin gene-related peptide, a specific marker for sensory neurons. These findings extend our previous observations in that not only beta-endorphin and Met-enkephalin (mu- and delta-receptor ligands), but also a preferential kappa-ligand is present within inflamed subcutaneous tissue.

Possible regulatory role of dynorphin A in the urinary bladder

Muscle strips from rat and human detrusor were studied using indirect immunofluorescence and electrical nerve stimulation in an organ bath. Immunoreactivity towards dynorphin was observed in varicose nerve fibres in the detrusor muscle and around immunonegative nerve cell bodies in the prevesical ganglia of the rat. In vitro, dynorphin A (1-13) (10(-13)-10(-6) M) strongly facilitated detrusor contraction induced by electrical field stimulation (EFS). This facilitation was counteracted by morphine (10(-10) and 10(-8) M) and naloxone (10(-10) and 10(-8) M) in a competitive manner. The facilitation could also be counteracted by the addition of the kappa-receptor antagonist M(r) 2266 (10(-7) M). Muscarinic blockade, achieved with atropine (10(-6) M), did not alter the effect of dynorphin A (1-13). Addition of phentolamine mesylate (10(-6) M), and propranolol (10(-6) M) per se facilitated the EFS-induced contractions. Both adrenergic blockade as well as the addition of the substance P blocker spantide, counteracted the facilitating effect of dynorphin A (1-13).

IN CONCLUSION

Dynorphin A immunoreactive material was found to be present in nerves in the rat detrusor and in prevesical ganglia. Dynorphin A (1-13) facilitated the detrusor contraction, possibly via actions on kappa-opioid receptors and interaction with non-cholinergic nerves.

Histamine release from rat mast cells induced by econazole

1. Econazole released histamine from rat mast cells in vitro. This response was not affected by the addition of calcium or by prior treatment of mast cells with EDTA or cromoglycate. 2. Rat mast cells treated with econazole were stained by the vital dye trypan blue. 3. The intradermal injection of econazole increased vascular permeability. This response was antagonized by chlorpheniramine and cyproheptadine. 4. Our results demonstrate that econazole releases histamine by the "nonselective" mechanism. It is suggested that econazole inflammatory effects may be due to histamine release from mast cells.

Rapid purification and characterization of histatins (histidine-rich polypeptides) from human whole saliva

Three different polypeptides capable of stimulating histamine release from mast cells were isolated from human whole saliva, using heparin-gel chromatography followed by reversed-phase HPLC. The amino acid sequences of these peptides were shown to be identical to those of histatins 1, 3 and 5.

Characteristics of beta-endorphin-induced histamine release from rat serosal mast cells. Comparison with neurotensin, dynorphin and compound 48/80

Rat peritoneal mast cells were exposed to the neurohormone and basic opioid peptide beta-endorphin. beta-Endorphin induced a dose-dependent release of histamine from the mast cells. A significant histamine release was found at 5 mumol/l of beta-endorphin and maximal release (35% of total) at 20 mumol/l. The histamine release process was very rapid and terminated within 30 s at 37 C, and in this sense is very similar to the histamine release induced by compound 48/80 or neurotensin. The histamine release was temperature-dependent showing an optimum release around 30 C, and it was independent of available extracellular calcium, but was inhibited in the presence of high extracellular calcium concentrations. Naloxone, only in very high concentrations (10 mmol/l), inhibited the release, and the very same concentration also inhibited the neurotensin - as well as the compound 48/80-induced histamine release. Cromoglycate and benzalkoniumchloride, a 48/80 antagonist, both produced a progressive dose-dependent inhibition of beta-endorphin-, neurotensin- as well as compound 48/80-induced histamine release. Taken together, the findings indicate that the opioid peptide beta-endorphin induces a selective, energy-dependent release of histamine from peritoneal rat mast cells. The pattern of release has much in common with that of compound 48/80 and other basic peptides, such as neurotensin and substance P. In addition this pattern of release is similar to that induced by dynorphin.

Is ascites caused by impaired hepatic inactivation of blood borne endogenous opioid peptides?

Methionine enkephalin and catecholamines were measured in carefully collected plasma samples from 25 patients with cirrhosis and ascites, and 25 with cirrhosis without ascites, 15 disease and 15 healthy controls. Methionine enkephalin was invariably raised in the ascites group, the median value being 4.6-6.9 times that of the other three groups. Similarly, in the ascites group, median noradrenaline was increased 2.5-4.2 and median adrenaline 1.8-2.5 times that of the other groups. Plasma methionine enkephalin is considerably raised in patients with cirrhotic ascites and has actions which could enable it to be an initiating factor of ascites formation.

Opioid peptides modulate immune functions. A review

In the past few years it has become evident that neuropeptides may be direct mediators in the modulation of the immune response and the unspecific defense by the brain. Lymphocytes have been thought to have opioid receptors and to respond to opioids with an increase in blastogenesis, cytotoxicity and factor release. Lymphocytes are said to release various neuropeptides. Furthermore, there are some unexplained effects of morphine on the immune system and of the immune system on morphine withdrawal. The purpose of this paper is to review what has been previously published in this field. The well established modulation of phagocyte functions by opioids will only be scanned.

Mast cell activation--a receptor-independent mode of substance P action?

Substance P is a representative of a group of amphiphilic neuropeptides which act as mast cell secretagogues. Our experiments with some new substance P derivatives suggest that these effects are dependent on two structural elements: (i) a hydrophobic chain which is not essentially a peptide, and (ii) a hydrophilic part with two positively charged amino acids. The mast cell triggering effect is unlikely to be mediated by a selective substance P receptor, but has strong similarities to the mode of action of polycations.

Pathway-specific patterns of the co-existence of substance P, calcitonin gene-related peptide, cholecystokinin and dynorphin in neurons of the dorsal root ganglia of the guinea-pig

The co-existence of immunoreactivities to substance P (SP), calcitonin gene-related peptide (CGRP), cholecystokinin (CCK) and dynorphin (DYN) in neurons of the dorsal root ganglion (DRG) of guinea-pigs has been investigated with a double-labeling immunofluorescence procedure. Four main populations of neurons could be identified that contained different combinations of these peptides and had distinctive peripheral projections: (Neurons that contained immunoreactivity to SP, CGRP, CCK and DYN were distributed mainly to the skin. Neurons with immunoreactivity to SP, CGRP and CCK, but not DYN, were distributed mainly to the small blood vessels of skeletal muscles. Neurons with immunoreactivity to SP, CGRP and DYN, but not CCK, were distributed mainly to pelvic viscera and airways. Neurons containing immunoreactivity to SP and CGRP, but not CCK and DYN, were distributed mainly to the heart, systemic blood vessels, blood vessels of the abdominal viscera, airways and sympathetic ganglia. Other small populations of DRG neurons containing SP, CGRP or CCK alone also were detected. Perikarya containing these combinations of neuropeptides were not found in autonomic ganglia. The peripheral axons of neurons containing immunoreactivity to at least SP and CGRP were damaged by chronic treatment with capsaicin. However, some sensory neurons containing CCK alone were not affected morphologically by capsaicin. These results clearly show that individual DRG neurons can contain many different neuropeptides. Furthermore, the combination of neuropeptides found in any particular neuron is related to its peripheral projection.

The effects of endorphins on mucous glycoprotein secretion from feline airways in vitro

The effect of opioid peptide hormones on respiratory glycoprotein secretion was investigated in a cat tracheal organ culture system. Dynorphin A (dyn, 10(-5) M), alpha-endorphin (alpha E, 10(-5) M) and morphine sulfate (MS, 10(-4) M) stimulated mucous glycoprotein (MGP) release from airways, whereas all other endorphins tested failed to have such an effect. Dyn did so in a dose dependent manner (10(-5)-10(-7) M) with a peak effect after a one hour incubation. Two sets of data suggest that dyn is acting through the previously described endorphin-kappa receptor: The active binding site of dyn is at the carboxyl end of the peptide; dyn fragment 1-13 stimulated MGP secretion while dyn fragment 1-8 did not. Naloxone in equimolar concentration totally inhibited the dyn response. We, therefore, conclude that the endorphins dyn and alpha E stimulate MGP release and that dyn is probably acting by stimulating kappa receptors.

A direct and sensitive determination of histamine in acid-deproteinized biological samples by high-performance liquid chromatography

A convenient method for the routine measurement of histamine (HA) in biological samples was developed. This method does not require any preliminary purification or concentration of HA, and features high sensitivity, specificity, and reliability. The method consists of the direct application of the acid-deproteinized sample to high-performance liquid chromatography on a sulfonated polystyrene column with detection by means of a postcolumn fluorogenic reaction with o-phthaladehyde. The detection limit was found to be 0.1 pmol (signal-to-noise ratio = 3). The coefficient of variation for measurements of 10 pmol of standard histamine was 1.1%. Each chromatography takes only 10 min and therefore more than 50 samples can be measured in a day. The high sensitivity of the method allows it to be applied even to samples of very low HA concentration such as human plasma without any procedure for concentration of the sample, and further, only 0.1 ml of the sample is necessary for determination. The method was applied to compare the HA levels of the whole blood and plasma of man and various animals. Applications of the method to the supernatant of rat peritoneal mast cell incubates and to extracts of mouse brain and stomach are also described.

Central and peripheral involvement of mu receptors in gastric secretory effects of opioids in the dog

The effects of dermorphin and morphine on gastric acid secretion were studied in conscious dogs with both gastric fistulas (GF) and Heidenhain pouches (HP). Under basal conditions dermorphin and morphine, infused systemically at graded doses, produced a significant increase in acid secretion from both GF and HP. This increase was significantly inhibited by naloxone, naltrexone methylbromide and N-methyl-levallorphan methanesulphonate. Dermorphin did not modify the acid output stimulated by 2-deoxy-D-glucose from GF, while morphine significantly inhibited it; on the contrary acid secretion from HP was increased in this test by both dermorphin and morphine. Acid secretion from GF stimulated by pentagastrin was unaffected by morphine and significantly enhanced by dermorphin. Under these conditions a significant increase in acid secretion from HP was recorded with dermorphin and morphine. Naloxone and N-methyl-levallorphan methanesulphonate, given during pentagastrin-stimulated secretion, significantly inhibited acid output 'per se' from GF and HP and prevented the stimulatory effect of dermorphin and morphine. Bethanechol-induced secretion from GF and HP was significantly increased by both dermorphin and morphine. The present results demonstrate that opioids have simultaneous yet opposite effects on acid secretion in the dog and that mu receptors are involved in both the excitatory and inhibitory effects. Excitatory effects do not seem to be mediated via a vagal pathway (peripheral ?), in contrast to the inhibitory effects (central ?). The inhibitory effects of opiate antagonists on pentagastrin-stimulated secretion suggest a physiological role of peripheral opioid receptors in gastric acid secretion.

Isolation and characterization of histamine-releasing peptides from human parotid saliva

Peptides responsible for releasing histamine were purified from human parotid saliva. The amino acid composition of the peptides showed a high proportion of histidine, lysine and arginine. Molecular weights of these peptides were between 3000 and 5000 as determined by SDS-acrylamide gel electrophoresis. These peptides induced histamine release from rat-isolated mast cells accompanied with degranulation in a dose-dependent manner over the concentration range 5-50 micrograms/ml.

Potency of various peptides as histamine liberators in the rat hind limb

The potency of several peptides and drugs as histamine liberators was assessed using the rat isolated hind limb preparation. Neurotensin (NT) and compound 48/80 (C48/80) were effective in concentrations as low as 10(-9) M and 10(-8) M, respectively. Threshold concentrations of vasoactive intestinal peptide (VIP) and substance P (SP) varied between 5 X 10(-7) to 5 X 10(-6) M while somatostatin (SS) was barely active at 6 X 10(-6) M. No histamine release could be detected following the use of high concentrations of thyrotropin releasing hormone (TRH) (6 X 10(-6) M), dynorphin (DYN) (6 X 10(-6) M) bradykinin (BK), des-Arg9-BK or bombesin (BB) (at 10(-5) M). Poly-L-Lysine and the calcium ionophore A23187 were about 100 times less active than NT. Concanavalin A (Con A) was inactive at 10(-6) M. These results indicate that NT is more potent (on a molar basis) as histamine liberator in the rat hind limb preparation (which contains a large population of cutaneous and subcutaneous mast cells) than any of the other compounds tested. Histamine release by NT was inhibited by preexposure of the rat hind limb mast cells to a high concentration of SP (1.5 X 10(-6) M). This result adds further support to the hypothesis suggesting that NT and SP might share a common mechanism of action and/or act through common receptors at least in rat mast cells.

Central and peripheral sites for cardiovascular actions of dynorphin-(1-13) in rats

Dynorphin-(1-13) (i.v.) induced bradycardia and hypotension in artificially ventilated anaesthetized rats. These effects were prevented by MRZ 2266 BS. The bradycardia was inhibited by bilateral vagotomy whereas the fall in blood pressure was not sensitive to bilateral vagotomy and chlorpheniramine treatment. In pithed rats, dynorphin-(1-13) reduced heart rate. This bradycardia was prevented by MRZ 2266 BS but not by tertatolol and cimetidine. It is suggested that the dynorphin-(1-13)-induced effects result from the stimulation of central and cardiac kappa-opiate receptors.