Rat Mast Cells Research Articles

Cathelicidin rCRAMP stimulates rat mast cells to generate cysteinyl leukotrienes, synthesize TNF and migrate: involvement of PLC/A2, PI3K and MAPK signaling pathways.

Cathelicidins represent a family of cationic peptides involved in host defense systems. Apart from exerting direct anti-microbial effects, cathelicidins can regulate immune responses by affecting the activity of cells playing a role in antibacterial defense. Taking into account that mast cells are critical components of host defense, the aim of this study was to determine whether rat cathelicidin-related anti-microbial peptide (rCRAMP) can influence mast cell activity. We have demonstrated that activation of fully mature rat mast cells with rCRAMP resulted in generation and release of cysteinyl leukotrienes (cysLTs). However, rCRAMP failed to induce mast cell degranulation and histamine release. We also found that rCRAMP stimulated rat mast cells to synthesize TNF, but not CXCL8. What is more, this peptide induced GM-CSF, IL-1β, CCL2 and CCL3 but not IL-33 mRNA expression in mast cells. Finally, we showed that this cathelicidin serves as potent chemoattractant for rat mast cells. rCRAMP-mediated cysLT synthesis and mast cell migration were strongly inhibited by IL-10 pre-treatment. With the use of specific inhibitors, we established that activation of PLC/A2 and ERK1/2, but not p38, was required for rCRAMP-induced mast cell stimulation, while PI3K-dependent pathway is involved in both TNF synthesis and mast cell migration. Our results suggest that cathelicidins can amplify inflammatory responses by causing mast cells accumulation and by stimulating these cells to release potent pro-inflammatory mediators.

Mast cell activation and response to tolterodine in the rat urinary bladder in a chronic model of intravesical protamine sulfate and bacterial endotoxin-induced cystitis.

The aim of the present study was to use an animal model of interstitial cystitis (IC) in order to investigate the histology and function of the bladder, with a particular focus on mast cell degranulation and response to detrusor overactivity (DO) to tolterodine. A total of 18female Sprague‑Dawley rats were used. In 12rats, lipopolysaccharide (LPS) was intravesically instilled following the induction of IC by protamine sulfate (PS) and sixrats were subjected to sham instillations. Following 1month, cystometry was performed. The effects of tolterodine were tested in half of the animals with IC. All rats in the IC group demonstrated DO during the filling phase and no significant changes in the frequency or pressure compared with that following tolterodine injection were identified. Histological examination revealed a significant increase in the total number of infiltrated mast cells in IC rats compared with that in the sham rats (P<0.05). Degranulated mast cells were evident in 80% of rats with IC; however, they were not apparent in the sham rats. Urinary bladder inflammation, similar to that in human IC in terms of degranulated mast cells and bladder function, was induced in rats. The animal model used in the present study provided insight into the pathophysiological mechanisms underlying the ineffectiveness of anticholinergics in patients with overlapping IC and overactive bladder (OAB).

Two-Dimensional Microchemical Observation of Mast Cell Biogenic Amine Release as Monitored by a 128 × 128 Array-Type Charge-Coupled Device Ion Image Sensor

Available array-type, chemical-sensing image sensors generally only provide on/off responses to the sensed chemical and produce qualitative information. Therefore, there is a need for an array sensor design that can detect chemical concentration changes to produce quantitative, event-sensitive information. In this study, a 128 × 128 array-type image sensor was modified and applied to imaging of biogenic amines released from stimulated rat mast cells, providing recordable responses of the time course of their release and diffusion. The imaging tool was manufactured by an integrated circuit process, including complementary metal oxide semiconductor and charge-coupled device technology. It was fitted with an amine-sensitive membrane prepared from plasticized poly(vinyl chloride) including a hydrophobic anion, which allowed the sensor to detect amines, such as histamine and serotonin, in Tyrode's solution. As mast cells were larger in diameter than the pixel hollows, some pixels monitored amines released from single cells. The image from the array responses yielded sequential snapshots at a practical frame speed that followed amine concentration changes over time, after mast cell amine release was synchronized by chemical stimulation. This sensor was shown to be sensitive to amine release at very low stimulus concentrations and was able to detect localized spots of high amine release. The entire time course of the amine release was recorded, including maximum concentration at 4-6 s and signal disappearance at 30 s after stimulation. With further development, this sensor will increase opportunities to study a variety of biological systems, including neuronal chemical processes.

Bitter taste receptor (TAS2R) agonists inhibit IgE-dependent mast cell activation

Bitter taste receptor (TAS2R) agonists inhibit IgE-dependent mast cell activation

Response and mast cell activation to tolterodine in protamine sulfate‐ and lipopolysaccaride‐treated rat urinary bladder (865.9)

We aimed to use an animal model of chronic interstitial cystitis in rats to investigate the histology and function of the bladder, with a special focus on mast cell degranulation and response of detrusor overactivity to tolterodine. A total of 18 female Sprague‐Dawley rats were used in this study. In 12 rats, lipopolysaccharide was intravesically instilled after the induction of interstitial cystitis by protamine sulfate; 6 rats were subjected to sham instillations. After 1 month, cystometry was performed in all rats with simultaneous registrations of intravesical and intraabdominal pressures. The effects of tolterodine on bladder function were tested in half of the interstitial cystitis animals. All rats in the interstitial cystitis group showed detrusor overactivity during the filling phase and no significant changes in frequency or pressure compared with that after tolterodine injection. Histological examination revealed a significant increase in total numbers of infiltrated mast cells in the interstitial cystitis rats compared with the sham rats (p&lt;0.05). Eighty percent of the interstitial cystitis rats showed degranulated mast cells, whereas the sham rats did not. Urinary bladder inflammation similar to that in human interstitial cystitis in terms of degranulated mast cells and bladder function was induced in Sprague‐Dawley rats. Our animal model should provide major insights into pathophysiologic mechanisms in the bladder, such as the mechanisms underlying the ineffectiveness of anticholinergics in patients with overlapping interstitial cystitis and overactive bladder.

Transcriptional regulation and proteolytic processing of perlecan in mast cells lead to the production of forms that contain the alpha2/beta1 integrin binding site: roles in wound healing and tissue regeneration (544.3)

This study demonstrated that primary human mast cells as well as the rat and human mast cell lines, RBL‐2H3 and HMC‐1, produce the heparan sulfate proteoglycan (HSPG), perlecan, with a Mr of 640kDa as well as smaller molecular weight species of 300 and 130kDa. Utilizing domain‐specific antibodies and N‐terminal sequencing we confirmed that both forms contained the C‐terminal module of the protein core, which were generated by mast cell‐derived proteases. Fractions from mast cell cultures that were enriched for these fragments were shown to bind endothelial cells via the alpha2/beta1 integrin and stimulate the migration of cells in “scratch assays”. Both of these activities were inhibited by incubation with antibodies reactive to the C‐terminus of the perlecan protein core. This study showed that the transcriptional regulation of the HSPG2 gene is more complex than first thought, particularly in mast cells. Domain specific RT‐PCR experiments demonstrated that these cells were capable of splicing the perlecan gene (HSPG2) and when we performed quantitative PCR experiments, we demonstrated that the C‐terminal region was over‐represented compared to the N‐terminal region. This together with the data demonstrating proteolytic processing suggest that the C‐terminal region of perlecan, which contains the alpha2/beta1 integrin binding site may have downstream biological functions that regulate angiogenesis and matrix turnover and thereby promote wound healing and tissue regenerative processes.

Escherichia coli Exposure Inhibits Exocytic SNARE‐Mediated Membrane Fusion in Mast Cells

Mast cells orchestrate the allergic response through the release of proinflammatory mediators, which is driven by the fusion of cytoplasmic secretory granules with the plasma membrane. During this process, SNARE proteins including Syntaxin4, SNAP23 and VAMP8 play a key role. Following stimulation, the kinase IKKβ interacts with and phosphorylates the t-SNARE SNAP23. Phosphorylated SNAP23 then associates with Syntaxin4 and the v-SNARE VAMP8 to form a ternary SNARE complex, which drives membrane fusion and mediator release. Interestingly, mast cell degranulation is impaired following exposure to bacteria such as Escherichia coli. However, the molecular mechanism(s) by which this occurs is unknown. Here, we show that E. coli exposure rapidly and additively inhibits degranulation in the RBL-2H3 rat mast cell line. Following co-culture with E. coli, the interaction between IKKβ and SNAP23 is disrupted, resulting in the hypophosphorylation of SNAP23. Subsequent formation of the ternary SNARE complex between SNAP23, Syntaxin4 and VAMP8 is strongly reduced. Collectively, these results demonstrate that E. coli exposure inhibits the formation of VAMP8-containing exocytic SNARE complexes and thus the release of VAMP8-dependent granules by interfering with SNAP23 phosphorylation.

Identification of anti-allergic effect of Clonorchis sinensis-derived protein venom allergen-like proteins (CsVAL)

Previous studies demonstrated that Clonochis sinensis-derived crude antigens suppress development of allergic responses. We investigated the effects of C. sinensis venom allergen-like (CsVAL) proteins on immune-modulating activities in allergic inflammatory response. Using RBL-2H3 rat mast cells, we demonstrated that CsVAL inhibits antigen-induced β-hexosaminidase release from immunoglobulin E-sensitized RBL-2H3 cells, and this inhibitory activity occurs by suppressing Lyn phosphorylation and intracellular reactive oxygen species production. In addition, CsVAL peptide treatment inhibits activation of protein kinase C-α and extracellular signal-regulated kinase 1/2, which are involved in degranulation of immunoglobulin E-sensitized mast cells. Furthermore, immunization with CsVAL suppressed development of skin inflammation by assessing ear thickness and cutaneous infiltration by eosinophils and mast cells in oxazolone-induced contact hypersensitivity in vivo mouse model. These results suggest that CsVAL is a promising candidate as an effective mast cell inhibitor for allergic and inflammatory diseases.

Palmitoylethanolamide inhibits rMCP-5 expression by regulating MITF activation in rat chronic granulomatous inflammation

Chronic inflammation, a condition frequently associated with several pathologies, is characterized by angiogenic and fibrogenic responses that may account for the development of granulomatous tissue. We previously demonstrated that the chymase, rat mast cell protease-5 (rMCP-5), exhibits pro-inflammatory and pro-angiogenic properties in a model of chronic inflammation sustained by mast cells (MCs), granuloma induced by the subcutaneous carrageenan-soaked sponge implant in rat. In this study, we investigated the effects of palmitoylethanolamide (PEA), an anti-inflammatory and analgesic endogenous compound, on rMCP-5 mRNA expression and Microphtalmia-associated Transcription Factor (MITF) activation in the same model of chronic inflammation. The levels of rMCP-5 mRNA were detected using semi-quantitative RT-PCR; the protein expression of chymase and extracellular signal-regulated kinases (ERK) were analyzed by western blot; MITF/DNA binding activity and MITF phosphorylation were assessed by electrophoretic mobility shift assay (EMSA) and immunoprecipitation, respectively. The administration of PEA (200, 400 and 800µg/ml) significantly decreased rMCP-5 mRNA and chymase protein expression induced by λ-carrageenan. These effects were associated with a significant decrease of MITF/DNA binding activity and phosphorylated MITF as well as phosphorylated ERK levels.In conclusion, our results, showing the ability of PEA to inhibit MITF activation and chymase expression in granulomatous tissue, may yield new insights into the understanding of the signaling pathways leading to MITF activation controlled by PEA.

Obtaining and Experimental Study of Candida Allergens

Due to the need of diagnostics of the widespread allergic diseases connected with infection ofa person by fungi, the question of creation of highly sensitive diagnostic panels of fungal allergens including molds and yeasts is important. Work purpose: creation of experimental technology of preparation of allergens from culture of C. albicans and studying of their physical, chemical and immunobiological properties. For receiving allergens we used the inactivated biomass of clinical strains of Candida albicans. Cultivation was carried out in the original mineral (without protein) CC1 and ML media in liquid and agarized variants with addition of sugar in various concentrations. In samples of allergens we defined amount of protein, carbohydrates, nucleic acids, specific activity in vitro (reaction of degranulation of rat mast cells). It was shown that the content of protein nitrogen varied from 72 to 18900 PNU, carbohydrates from 0,001 to 0,079 mg/ ml depending on physiological properties of a population of C. albicans and cultivation conditions. For determination of specific activity (reaction of rat mast cells degranulation) of samples used sera from patients with a sensitization to fungi. Allergenic activity of preparations in reaction of degranulation of rat mast cells varied from 3% (spontaneous) to 52%. The highest specific activity was shown for samples of the allergens obtained from C. albicans, grown in the ML medium. The results obtained using of 18 samples of preparations, can be a basis for a choice of an optimum technological mode of allocation of allergens from C. albicans.

Structure-activity relationship of a series of 17 parabens and related compounds for histamine release in rat peritoneal mast cells and skin allergic reaction in guinea pigs

Parabens, which are a homologous series of esters of p-hydroxybenzoic acid, have been used as preservatives in cosmetics, medicines and foods because of their antimicrobial activity. However, parabens in cosmetics have been suspected to cause allergic contact dermatitis. In this study, we examined paraben-induced histamine release from rat peritoneal mast cells and skin reaction in guinea pigs using a series of 17 parabens with different alcohol side chains, ranging from methylparaben to dodecylparaben. Octylparaben showed the greatest histamine release-inducing activity from mast cells, and the activity was decreased in shorter- and longer-side-chain parabens. Octyl benzoate, octyl o-hydroxybenzoate and phenyloctane caused no significant degranulation of mast cells, whereas octyl m-hydroxybenzoate, octyl p-hydroxybenzoate and octyl phenol induced concentration-related degranulation. Metabolites of these parabens (p-hydroxybenzoic acid and alcohols) did not show histamine release-inducing activity. In the guinea pig skin reaction test, heptylparaben induced a typical strong skin reaction, while butylparaben induced a typical weak skin reaction, and methylparaben and dodecylparaben were inactive. Metabolites of parabens (p-hydroxybenzoic acid and alcohols) were also inactive. These results indicate that interaction of parabens with rat mast cells requires a minimum length and adequate lipophilicity of the alkyl side chain. Since metabolites of parabens were inactive, parabens appear to be direct-acting allergens.

Disodium Cromoglycate Reverses Colonic Visceral Hypersensitivity and Influences Colonic Ion Transport in a Stress-Sensitive Rat Strain

The interface between psychiatry and stress-related gastrointestinal disorders (GI), such as irritable bowel syndrome (IBS), is well established, with anxiety and depression the most frequently occurring comorbid conditions. Moreover, stress-sensitive Wistar Kyoto (WKY) rats, which display anxiety- and depressive-like behaviors, exhibit GI disturbances akin to those observed in stress-related GI disorders. Additionally, there is mounting preclinical and clinical evidence implicating mast cells as significant contributors to the development of abdominal visceral pain in IBS. In this study we examined the effects of the rat connective tissue mast cell (CTMC) stabiliser, disodium cromoglycate (DSCG) on visceral hypersensitivity and colonic ion transport, and examined both colonic and peritoneal mast cells from stress-sensitive WKY rats. DSCG significantly decreased abdominal pain behaviors induced by colorectal distension in WKY animals independent of a reduction in colonic rat mast cell mediator release. We further demonstrated that mast cell-stimulated colonic ion transport was sensitive to inhibition by the mast cell stabiliser DSCG, an effect only observed in stress-sensitive rats. Moreover, CTMC-like mast cells were significantly increased in the colonic submucosa of WKY animals, and we observed a significant increase in the proportion of intermediate, or immature, peritoneal mast cells relative to control animals. Collectively our data further support a role for mast cells in the pathogenesis of stress-related GI disorders.

Amphipath-induced plasma membrane curvature controls microparticle formation from adipocytes: Novel therapeutic implications for metabolic disorders

Microparticles produced from the membrane surface of adipocytes promote lipid biosynthesis and angiogenesis in adipose tissues. Thus, they are deeply associated with the onset of metabolic disorders. Despite our understanding of their roles in physiological or pathological responses, we know little about the mechanism by which microparticles are produced from adipocytes. Based on our previous studies using rat megakaryocytes or mast cells during exocytosis, we proposed that membrane curvature induced by amphiphilic reagents, such as chlorpromazine or salicylate, facilitate or inhibit the formation of microparticles. Since the plasma membranes in adipocytes share many common biophysiological features with those in megakaryocytes or mast cells during exocytosis, the same stimulatory or inhibitory mechanism of microparticle formation would exist in adipocytes. Therefore, we hypothesize here that amphiphilic reagents would also change the membrane curvature in adipocytes, and that such changes would facilitate or inhibit the microparticle formation from adipocytes. Our hypothesis is unique because it sheds light for the first time on the physiological mechanism by which microparticles are produced in adipocytes. It is also important because the idea could have novel therapeutic implications for metabolic disorders that are triggered by increases in the microparticle formation.

Anti-inflammatory and anti-allergic activities of sea cucumber (Stichopus japonicus) extract

In this study, we investigated the anti-inflammatory and anti-allergic effects of Stichopus japonicus extract. The anti-inflammatory effect of S. japonicus was evaluated using the Griess reaction to evaluate nitric oxide (NO) release and reverse transcriptase-PCR (RT-PCR) to determine interleukin (IL)-6 and tumor necrosis factor-α (TNF-α) mRNA expression levels in LPS-stimulated RAW 264.7 murine macrophages. The anti-allergic activity of S. japonicus was investigated by performing β-hexosaminidase assay on antigen-stimulated RBL-2H3 rat mast cell lines and IL-4 mRNA expression. Our data revealed that S. japonicas water fraction (SJW) inhibited NO release without cytotoxicity in LPS-stimulated Raw 264.7 cells. The levels of IL-6 and TNF-α mRNA reduced following SJW treatment. In addition, SJW inhibited antigen-induced degranulation (e.g., IC50 value of 658 μg/mL) as well as IL-4 mRNA expression. Our results suggest that SJW possesses anti-inflammatory and anti-allergic effects.

The localisation of inflammatory cells and expression of associated proteoglycans in response to implanted chitosan

Implantation of a foreign material almost certainly results in the formation of a fibrous capsule around the implant however, mechanistic events leading to its formation are largely unexplored. Mast cells are an inflammatory cell type known to play a role in the response to material implants, through the release of pro-inflammatory proteases and cytokines from their α-granules following activation. This study examined the in vivo and in vitro response of mast cells to chitosan, through detection of markers known to be produced by mast cells or involved with the inflammatory response. Mast cells, identified as Leder stained positive cells, were shown to be present in response to material implants. Additionally, the mast cell receptor, c-kit, along with collagen, serglycin, perlecan and chondroitin sulphate were detected within the fibrous capsules, where distribution varied between material implants. In conjunction, rat mast cells (RBL-2H3) were shown to be activated following exposure to chitosan as indicated by the release of β-hexosaminidase. Proteoglycan and glycosaminoglycans produced by the cells showed similar expression and localisation when in contact with chitosan to when chemically activated. These data support the role that mast cells play in the inflammatory host response to chitosan implants, where mediators released from their α-granules impact on the formation of a fibrous capsule by supporting the production and organisation of collagen fibres.

IgE by Itself Affects Mature Rat Mast Cell Preformed and De Novo-Synthesized Mediator Release and Amplifies Mast Cell Migratory Response

BackgroundImmunoglobulin E (IgE) binds to high affinity receptor FcεRI numerously expressed on mast cells. Recent findings have revealed that IgE by itself may regulate various aspects of mast cell biology, however, detailed data is still limited.Methodology/FindingsHere, we have examined the influence of IgE alone, used at different concentrations, on mast cell activity and releasability. For the study we have employed in vivo differentiated mature tissue mast cells isolated from rat peritoneal cavity. Mast cells were exposed to IgE alone and then the release of preformed and de novo-synthesized mediators, surface FcεRI expression and mast cell migratory response were assessed. IgE by itself was found to up-regulate FcεRI expression and activate mast cells to degranulation, as well as de novo synthesis and release of cysteinyl leukotrienes and TNF. We have provided evidence that IgE alone also amplified spontaneous and CCL5- or TNF-induced migration of mast cells. Importantly, IgE was effective only at concentrations ≥ 3 µg/mL. A molecular basis investigation using an array of specific inhibitors showed that Src kinases, PLC/PLA2, MAP kinases (ERK and p38) and PI3K were entirely or partially involved in IgE-induced mast cell response. Furthermore, IgE alone stimulated the phosphorylation of MAP kinases and PI3K in rat mast cells.ConclusionOur results clearly demonstrated that IgE by itself, at higher concentrations, influences mast cell activity and releasability. As there are different conditions when the IgE level is raised it might be supposed that in vivo IgE is one of the important factors modulating mast cell biology within tissues.

Human mast cell line-1 (HMC-1) cells exhibit a membrane capacitance increase when dialysed with high free-Ca2+ and GTPγS containing intracellular solution

An increase in cytosolic free calcium concentration [Ca2+]i initiates the exocytotic activity in various types of secretory cells. The guanosine 5′-O-[3-thio]triphosphate (GTPγS), a non-hydrolysable analogue of GTP (guanosine 5′-triphosphate), is an effective secretagogue for different cell types of different species, like mast cells, neutrophils or eosinophils. Consequently, the internal administration of GTPγS causes degranulation of mouse and rat mast cells. Regarding rat mast cells, it is proved that Ca2+ can cooperate with GTP or GTPγS in accelerating and increasing amplitude of the secretory response. All the previous studies with respect to capacitance recordings and mast cells were performed using mouse or rat mast cells, usually derived from peritoneum or the rat basophilic leukaemia cell line RBL. In this study, we applied the capacitance measurement technique to the human mast cell line-1 (HMC-1) cells, an immature cell line established from a patient with mast cell leukaemia. Patch-clamp dialysis experiments revealed that high intracellular free Ca2+ and GTPγS concentrations are both required for considerable capacitance increases in HMC-1 cells. During degranulation of HMC-1 cells, the total membrane capacitance (Cm) increase appeared continuously and, in some cases, as a discrete capacitance change, developing in a stepwise manner. Then, we tested the effect of latrunculin B upon HMC-1 cell capacitance increase as well as of some classic mast cell stimulators like PMA, A23187 and IL-1β in hexosaminidase release. Finally, we could conclude that the HMC-1 cell line represents a suitable model for the study of human mast cell degranulation.

Stimulated mast cells promote maturation of myocardial microvascular endothelial cell neovessels by modulating the angiopoietin-Tie-2 signaling pathway

Angiopoietin (Ang)-1 and Ang-2 interact in angiogenesis to activate the Tie-2 receptor, which may be involved in new vessel maturation and regression. Mast cells (MCs) are also involved in formation of new blood vessels and angiogenesis. The present study was designed to test whether MCs can mediate angiogenesis in myocardial microvascular endothelial cells (MMVECs). Using a rat MMVEC and MC co-culture system, we observed that Ang-1 protein levels were very low even though its mRNA levels were increased by MCs. Interestingly, MCs were able to enhance migration, proliferation, and capillary-like tube formation, which were associated with suppressed Ang-2 protein expression, but not Tie-2 expression levels. These MCs induced effects that could be reversed by either tryptase inhibitor [N-tosyl-L-lysine chloromethyl ketone (TLCK)] or chymase inhibitor (N-tosyl-L-phenylalanyl chloromethyl ketone), with TLCK showing greater effects. In conclusion, our data indicated that MCs can interrupt neovessel maturation via suppression of the Ang-2/Tie-2 signaling pathway.

Eosinophil major basic protein activates human cord blood mast cells primed with fibroblast membranes by integrin‐β1

Mast cell (MC) - eosinophil (Eos) activating cross-talk might be critical for the severity and chronicity of allergy. Among soluble mediators, eosinophil major basic protein (MBP), a hallmark of allergy, is particularly important because it was shown to activate specific MC subtypes. We previously demonstrated that MBP activates IgE-desensitized rat MC and human lung and cord blood-derived MC (CBMC) after priming with fibroblast membranal stem cell factor. However, a distinct mechanism for this activation was missing. Therefore, we aimed to investigate it. Major basic protein-1 activation of CBMC primed with fibroblast-derived membranes (FBM) was measured by β-hexosaminidase and tryptase release. Chemical cross-linking followed by micrometric flow cytometry probed direct interactions. Antibodies neutralized integrin-β1 and recognized its active form. Pertussis toxin (Ptx) was used to decrease integrin-β1 active form expression. Hematopoietic cell kinase (Hck) was identified by immunoprecipitation (IP) and silenced by siRNA. Major basic protein-1-induced CBMC activation is mediated partly by MBP1-integrin-β1 interaction on the MC surface. FBM prime CBMC via a G protein, as confirmed by Ptx, to shift integrin-β1 to its active form. Following MBP1 binding, integrin-β1 binds Hck that further transduces the activation signal. MC priming with FBM leads to up-regulation in Hck protein level. MC integrin-β1 neutralization inhibits MBP1-induced activation and uptake. Hck silencing results with reduced MBP1-induced activation. Fibroblast-derived membranes, integrin-β1, and Hck are involved in MBP1-induced activation of CBMC and therefore represent a distinct mechanism for this activation. This finding might implicate integrin-β1 and Hck as targets for decreasing MC - Eos activating cross-talk in allergy.

In Vitro Hematological and In Vivo Vasoactivity Assessment of Dextran Functionalized Graphene

The intravenous, intramuscular or intraperitoneal administration of water solubilized graphene nanoparticles for biomedical applications will result in their interaction with the hematological components and vasculature. Herein, we have investigated the effects of dextran functionalized graphene nanoplatelets (GNP-Dex) on histamine release, platelet activation, immune activation, blood cell hemolysis in vitro, and vasoactivity in vivo. The results indicate that GNP-Dex formulations prevented histamine release from activated RBL-2H3 rat mast cells, and at concentrations ≥ 7 mg/ml, showed a 12–20% increase in levels of complement proteins. Cytokine (TNF-Alpha and IL-10) levels remained within normal range. GNP-Dex formulations did not cause platelet activation or blood cell hemolysis. Using the hamster cheek pouch in vivo model, the initial vasoactivity of GNP-Dex at concentrations (1–50 mg/ml) equivalent to the first pass of a bolus injection was a brief concentration-dependent dilation in arcade and terminal arterioles. However, they did not induce a pro-inflammatory endothelial dysfunction effect.