Effects of dimethylsulfoxide (DMSO), nocodazole, and taxol on mast cell histamine secretion

Cytoskeletal Transport, Reorganization, and Fusion Regulation in Mast Cell-Stimulus Secretion Coupling

Mast cells are well known for their role in allergies and many chronic inflammatory diseases. They release upon stimulation, e.g., via the IgE receptor, numerous bioactive compounds from cytoplasmic secretory granules. The regulation of granule secretion and its interaction with the cytoskeleton and transport mechanisms has only recently begun to be understood. These studies have provided new insight into the interaction between the secretory machinery and cytoskeletal elements in the regulation of the degranulation process. They suggest a tight coupling of these two systems, implying a series of specific signaling effectors and adaptor molecules. Here we review recent knowledge describing the signaling events regulating cytoskeletal reorganization and secretory granule transport machinery in conjunction with the membrane fusion machinery that occur during mast cell degranulation. The new insight into MC biology offers novel strategies to treat human allergic and inflammatory diseases targeting the late steps that affect harmful release from granular stores leaving regulatory cytokine secretion intact.

Class I PI3K-mediated Akt and ERK signals play a critical role in FcεRI-induced degranulation in mast cells

Class IA and IB phosphoinositide 3-kinases (PI3Ks) have been shown to regulate mast cell functions such as proliferation, development, survival and degranulation, but the functional redundancy between these two PI3K signaling pathways in mast cells remains unclear. Here, we have generated mice deficient in both class IA regulatory subunit p85α and class IB catalytic subunit p110γ, and show that p85α(-/-)p110γ(-/-) mice exhibit a more severe defect in mast cell development than single-knockout mice. In addition, the in vivo passive cutaneous anaphylaxis reaction of p85α(-/-)p110γ(-/-) mice was nearly completely abrogated, whereas single-knockout mice exhibit just marginal reduction. Pharmacological inactivation of Akt in wild-type bone marrow-derived mast cells (BMMCs) led to partial reduction of degranulation, while over-expression of a constitutively active Akt partially restored the impaired degranulation in p85α(-/-)p110γ(-/-) BMMCs. We also found that the extracellular signal-regulated kinase (ERK) signaling pathway was activated in a PI3K-dependent manner upon FcεRI stimulation and that simultaneous inhibition of Akt and ERK resulted in nearly complete blockade of FcεRI-induced degranulation. Our data provide evidence that Akt and ERK pathways play redundant roles in FcεRI-induced degranulation.

Fc{epsilon}RI-mediated mast cell degranulation requires calcium-independent microtubule-dependent translocation of granules to the plasma membrane

The aggregation of high affinity IgE receptors (Fcɛ receptor I [FcɛRI]) on mast cells is potent stimulus for the release of inflammatory and allergic mediators from cytoplasmic granules. However, the molecular mechanism of degranulation has not yet been established. It is still unclear how FcɛRI-mediated signal transduction ultimately regulates the reorganization of the cytoskeleton and how these events lead to degranulation. Here, we show that FcɛRI stimulation triggers the formation of microtubules in a manner independent of calcium. Drugs affecting microtubule dynamics effectively suppressed the FcɛRI-mediated translocation of granules to the plasma membrane and degranulation. Furthermore, the translocation of granules to the plasma membrane occurred in a calcium-independent manner, but the release of mediators and granule–plasma membrane fusion were completely dependent on calcium. Thus, the degranulation process can be dissected into two events: the calcium-independent microtubule-dependent translocation of granules to the plasma membrane and calcium-dependent membrane fusion and exocytosis. Finally, we show that the Fyn/Gab2/RhoA (but not Lyn/SLP-76) signaling pathway plays a critical role in the calcium-independent microtubule-dependent pathway.

Modulation of gastric hemorrhage and ulceration by oxidative stress and histamine release in Salmonella typhimurium-infected rats

Infection with Salmonella typhimurium can produce multiple organ dysfunctions. However, document concerning with gastric hemorrhagic ulcers occur in this infectious disease is lacking. The aim was to study modulation of gastric hemorrhagic ulcer by oxidative stress and mast cell histamine in S. typhimurium-infected rats. Additionally, the protective effects of drugs, such as ofloxacin, lysozyme chloride, ketotifen, ranitidine, and several antioxidants, including exogenous glutathione (GSH), allopurinol and dimethylsulfoxide (DMSO) were evaluated. Male Wistar rats were injected intrajejunally with a live culture of S. typhimurium (1 x 10(10) colony-forming units/rat) and followed by deprivation of food for 36 h. Age-matched control rats received sterilized vehicle only. Rat stomachs were irrigated for 3 h with either normal saline or a simulated gastric juice containing 100 mM HCl, 17.4 mM pepsin and 54 mM NaCl. S. typhimurium caused aggravation of offensive factors, including enhancing gastric acid back-diffusion, mucosal lipid peroxide generation, histamine release, microvascular permeability and hemorrhagic ulcer, as well as an attenuation of defensive substances, such as mucosal GSH and mucus level. Intragastric irrigation of gastric juice caused further aggravation of these gastric biochemical parameters. This exacerbation of ulcerogenic factors was abolished by pretreatment of ofloxacin and lysozyme chloride. Antioxidants, such as reduced GSH, allopurinol and DMSO also produced significant (P < 0.05) amelioration of gastric damage in S. typhimurium infected rats. In conclusion, gastric oxidative stress and histamine play pivotal roles in the formation of hemorrhagic ulcers that were effectively ameliorated by ofloxacin, lysozyme chloride, ketotifen, ranitidine, diamine oxidase and various antioxidants in S. typhimurium-infected rats.

Gastric oxidative stress and hemorrhagic ulcer in Salmonella typhimurium-infected rats

Infection of Salmonella typhimurium (Salmonella typhi) can lead to various organ diseases. This research first proposed that Salmonella typhi-infection could result in gastric oxidative stress and hemorrhagic ulcers that were ameliorated by ofloxacin, lysozyme chloride and several antioxidants, including exogenous glutathione (GSH), allopurinol and dimethylsulfoxide (DMSO). Male Wistar rats were given intrajejunally the live culture of Salmonella typhi [1 x 10(10) colony-forming unit (CFU)/rat] and followed by deprivation of food for 36 h. Age-matched control rats received vehicle only. Rat stomachs were irrigated for 3 h with either normal saline or a simulated gastric juice containing 100 mM HCl, 17.4 mM pepsin and 54 mM NaCl. Infection of Salmonella typhi produced an aggravation of ulcerogenic factors, including enhancing gastric acid back-diffusion, mucosal lipid peroxide generation and hemorrhagic ulcer as well as an attenuation of mucosal GSH level. Intragastric irrigation of gastric juice caused further aggravation of these gastric biochemical parameters. This exacerbation of ulcerogenic factors was abolished by pretreatment of ofloxacin and lysozyme chloride. Antioxidants, such as reduced GSH, allopurinol and DMSO also produced significant (P<0.05) amelioration of gastric damage in Salmonella typhi-infected rats. In conclusion, infection of Salmonella typhi substantially caused gastric oxidative stress and disruption of gastric mucosal barriers, consequently resulted in gastric hemorrhagic ulcerations that were effectively ameliorated by ofloxacin, lysozyme chloride and various antioxidants.

Evidence of a role for Munc18-2 and microtubules in mast cell granule exocytosis

Compound exocytosis of inflammatory mediators from mast cells requires SNARE and a series of accessory proteins. However, the molecular steps that regulate secretory granule movement and membrane fusion as well as the role of the cytoskeleton are still poorly understood. Here, we report on our investigation of the role of syntaxin-binding Munc18 isoforms and the microtubule network in this process. We found that mast cells express Munc18-2, which interacts with target SNAREs syntaxin 2 or 3, as well as Munc18-3, which interacts with syntaxin 4. Munc18-2 was localised to secretory granules, whereas Munc18-3 was found on the plasma membrane. Increased expression of Munc18-2 and derived peptides containing an interfering effector loop inhibited IgE-triggered exocytosis, while increased expression of Munc18-3 showed no effect. Munc18-2 localisation on granules is polarised; however, upon stimulation Munc18-2 redistributed into forming lamellipodia and persisted on granules that were aligned along microtubules, but was excluded from F-actin ruffles. Disruption of the microtubule network with nocodazole provoked Munc18-2 redistribution and affected mediator release. These findings suggest a role for Munc18-2 and the microtubule network in the regulation of secretory granule dynamics in mast cells.

Importance of histamine, glutathione and oxyradicals in modulating gastric haemorrhagic ulcer in septic rats

1. The ulcerogenesis of gastric haemorrhagic damage during sepsis is unclear. The present study first proposes that gastric haemorrhagic ulcer is modulated by mucosal glutathione, histamine and oxyradicals in lipopolysaccharide (LPS)-induced sepsis in rats. The protective effects of several drugs on the ulcerogenic parameters also were evaluated. 2. Male specific pyrogen-free Wistar rats were deprived of food for 24 h. For the induction of sepsis, intravenous LPS (0, 1, 3 or 10 mg/kg in 1 mL sterilized normal saline) was challenged to rats 12 h after withdrawal of food. Rat stomachs were vagotomized, followed by irrigation for 3 h with normal saline or a physiological acid solution containing 100 mmol/L HCI and 54 mmol/L NaCl. 3. The aggravation of gastric ulcerogenic parameters, such as gastric acid back-diffusion, luminal haemoglobin content, mucosal lipid peroxide production, histamine concentration, as well as lowered concentrations of defensive substances, including mucosal glutathione, were dependent on the doses of LPS used for challenge. A high correlation was observed between mucosal histamine release and lipid peroxide production in LPS rats. 4. The ulcerogenic parameters obtained in LPS (3 mg/kg, i.v.) rats were potently attenuated by diamine oxidase, ketotifen and zinc sulphate. 5. Several oxyradical scavengers, including glutathione, dimethylsulphoxide and allopurinol, also were effective in inhibiting haemorrhagic ulcer. 6. In conclusion, gastric mucosal histamine release and oxyradical generation play pivotal roles in the formation of haemorrhagic ulcers in septic rats.

Suppression of anaphylactic shock in sensitized guinea pigs by cytochalasin D

A new highly effective pathogenetic therapy for anaphylactic reaction in vivo has been suggested. Forty-three guinea pigs, presensitized with horse serum and divided into two groups, were injected intracardially with 1 ml of 1.6 x 10(-4) M cytochalasin D and 1 ml of 1.6 x 10(-5) M cytochalasin D in DMSO solution at various times before being challenged with the serum. Experimental data not only showed that anaphylactic reaction can be suppressed in vivo by blocking cytoskeletal activity but also demonstrated different pharmacodynamic characteristics of cytochalasin D on clinical course, gravity and outcome of anaphylactic shock in sensitized guinea pigs, depending on the interval between administration of the drug and allergen.

Unusual effects of the ionophore A23187 at suboptimal concentrations in mast cell histamine release

Certain peculiarities are observed in connection with histamine release induced by suboptimal concentrations of the ionophore A23187. The potency of the ionophore can increase by a factor of 3 when added to the incubation medium from solutions in either DMSO or buffer without added calcium as compared with addition from standard buffer. The effect was not due to the solvent per se but may relate to physicochemical conditions facilitating the ionophore's access to cellular domains.

Dimethyl sulfoxide decreases the fluorescence yield of the reaction between histamine and ortho-phthalaldehyde and may influence histamine release

A sensitive method for quantifying histamine is the assay based on the fluorescence of the product obtained after reacting the amine with ortho-phthalaldehyde. The presence of dimethyl sulfoxide (DMSO) even in concentrations as low as 1% decreases the yield of fluorescence. Neglecting this quenching leads to the erroneous conclusion that DMSO in a concentration dependent manner inhibits the thapsigargin induced histamine release from peritoneal rat mast cells. Apart from the release induced by the selective calcium ion mobilizers thapsigargin and ionophore A23147, DMSO potently inhibits the response to other secretagogues.