Differential regulation of mast cell cytokines by both dexamethasone and the p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580

Nutritional and Behavioral Countermeasures as Medication Approaches to Relieve Motion Sickness: A Comprehensive Review

The mismatch in signals perceived by the vestibular and visual systems to the brain, also referred to as motion sickness syndrome, has been diagnosed as a challenging condition with no clear mechanism. Motion sickness causes undesirable symptoms during travel and in virtual environments that affect people negatively. Treatments are directed toward reducing conflicting sensory inputs, accelerating the process of adaptation, and controlling nausea and vomiting. The long-term use of current medications is often hindered by their various side effects. Hence, this review aims to identify non-pharmacological strategies that can be employed to reduce or prevent motion sickness in both real and virtual environments. Research suggests that activation of the parasympathetic nervous system using pleasant music and diaphragmatic breathing can help alleviate symptoms of motion sickness. Certain micronutrients such as hesperidin, menthol, vitamin C, and gingerol were shown to have a positive impact on alleviating motion sickness. However, the effects of macronutrients are more complex and can be influenced by factors such as the food matrix and composition. Herbal dietary formulations such as Tianxian and Tamzin were shown to be as effective as medications. Therefore, nutritional interventions along with behavioral countermeasures could be considered as inexpensive and simple approaches to mitigate motion sickness. Finally, we discussed possible mechanisms underlying these interventions, the most significant limitations, research gaps, and future research directions for motion sickness.

Potential Predictive Value of miR-125b-5p, miR-155-5p and Their Target Genes in the Course of COVID-19

Purpose

This study aimed to provide new biomarkers for predicting the disease course of COVID-19 by analyzing the dynamic changes of microRNA (miRNA) and its target gene expression in the serum of COVID-19 patients at different stages.

Methods

Serum samples were collected from all COVID-19 patients at three time points: the acute stage, the turn-negative stage, and the recovery stage. The expression level of miRNA and the target mRNA was measured by Quantitative Real-Time Polymerase Chain Reaction (RT-qPCR). The classification tree model was established to predict the disease course, and the prediction efficiency of independent variables in the model was analyzed using the receiver operating characteristic (ROC) curve.

Results

The expression of miR-125b-5p and miR-155-5p was significantly up-regulated in the acute stage and gradually decreased in the turn-negative and recovery stages. The expression of the target genes CDH5, STAT3, and TRIM32 gradually down-regulated in the acute, turn-negative, and recovery stages. MiR-125b-5p, miR-155-5p, STAT3, and TRIM32 constituted a classification tree model with 100% accuracy of prediction and AUC >0.7 for identification and prediction in all stages.

Conclusion

MiR-125b-5p, miR-155-5p, STAT3, and TRIM32 could be useful biomarkers to predict the time nodes of the acute, turn-negative, and recovery stages of COVID-19.

The Critical Role Played by Mitochondrial MITF Serine 73 Phosphorylation in Immunologically Activated Mast Cells

In recent years, growing evidence has indicated the pivotal role of mitochondria in mast cell immunological activation. We have previously reported a decrease in degranulation and cytokine secretion following the inhibition of pyruvate dehydrogenase (PDH) either by CPI-613 (PDH inhibitor/anti-cancer drug) or through its interaction with mitochondrial microphthalmia-associated transcription factor (MITF). In the present study, we further explored the role played by mitochondrial MITF in mast cell exocytosis using rat basophil leukemia cells [RBL], as well as mouse bone marrow-derived mast cells (BMMCs). Here, we report that mast cell degranulation, cytokine secretion and oxidative phosphorylation (OXPHOS) activities were associated with phosphorylation of Serine 73 of mitochondrial MITF, controlled by extracellular signals regulated by protein kinase (ERK1/2) activity. Also, we report here that decreased OXPHOS activity following ERK1/2 inhibition (U0126 treatment) during IgE-Ag activation was mediated by the dephosphorylation of Serine 73 mitochondrial MITF, which inhibited its association with PDH. This led to a reduction in mast cell reactivity. In addition, a phosphorylation-mimicking mitochondrial MITF-S73D positively regulated the mitochondrial activity, thereby supporting mast cell degranulation. Thus, the present research findings highlight the prominence of mitochondrial MITF Serine 73 phosphorylation in immunologically activated mast cells.

Circulating plasma miR-155 is a potential biomarker for the detection of SARS-CoV-2 infection

Identification of human miRNAs involved in coronavirus-host interplay is important due to the current COVID-19 pandemic. Therefore, this study aimed to measure the circulating plasma miR-155 expression level in COVID-19 patients and healthy controls to investigate its roles in the pathogenesis and severity of COVID-19 disease and to assess its usefulness as a clinical biomarker for the detection of COVID-19 disease and the severity of infection.

A total of 150 COVID-19 patients and 50 controls were enrolled into our study. Beside the routine laboratory work and chest computed tomography (CT) scans of COVID-19 patients, plasma miR-155 expression level was measured using reverse transcription quantitative real-time PCR (RT-qPCR) technique.

Our results demonstrated increased miR-155 expression level in COVID-19 patients compared to controls, in severe compared to moderate COVID-19 patients, and in non-survival compared to survival COVID-19 patients. miR-155 expression level also had significant correlation with clinicopathological characteristics of COVID-19 patients such as chest CT findings, CRP, ferritin, mortality, D-dimer, WBC count, and lymphocytes and neutrophils percentages. Also, our results showed that the area under the curve (AUC) for miR-155 was 0.986 with 90% sensitivity and 100% specificity when used as a biomarker for the detection of COVID-19 disease; while in detection of severity of COVID-19 disease, AUC for miR-155 was 0.75 with 76% sensitivity and specificity.

From these results we can conclude that miR-155 has a crucial role in the pathogenesis and severity of COVID-19; also, it could be a good diagnostic clinical biomarker for the detection of COVID-19 disease and the severity of infection.

Cytokine Stimulation via MRGPRX2 Occurs with Lower Potency than by FcεRI-aggregation but with Similar Dependence on the ERK1/2 Module in Human Skin Mast Cells

Skin mast cells (MCs) contribute to chronic dermatoses that partially rely on MC-derived cytokines. The discovery of MRGPRX2 explains MC-dependent symptoms independently of FcεRI-activation. Here, we investigated whether MRGPRX2 can elicit cytokines, determined its relative potency versus FcεRI and addressed the underlying mechanisms. MRGPRX2-activation by compound 48/80 or Substance P on skin MCs induced TNF-α, IL-8, IL-13, CCL1, CCL2 mRNA and protein, yet induction was typically reduced compared with FcεRI-crosslinking. Generally, cytokine secretion required de-novo-synthesis with maximum accumulation at ≈8 h. Addressing key kinases revealed robust, rapid (1 min), and lasting (30 min) phosphorylation of ERK1/2 following MRGPRX2-ligation, while pp38, and pAKT signals were weaker, and pJNK hardly detectable. The kinase spectrum following FcεRI-aggregation was comparable, but responses considerably delayed. The MEK/ERK pathway was essential for all cytokines examined and four inhibitors of this module gave complete suppression. Variable and weaker contribution was found for PI3K>JNK>p38. Strikingly, cytokine profiles and signaling prerequisites were similar for MRGPRX2 and FcεRI and likely mainly dictated by the MC subset. Collectively, in skin MCs, the physiological producers of MRGPRX2, agonist binding elicits cytokines, yet less efficiently than FcεRI-aggregation. MRGPRX2-associated inflammation may thus be less tissue-destructive than responses to allergic challenge.

Resiniferatoxin promotes adult worm expulsion in Trichinella spiralis-infected rats by Th2 immune response modulation

BACKGROUND

The immune response during T spiralis infection is characterized by an increase in eosinophils and mast cells, as well as Th2 cytokine production, such as interleukin (IL)-4, IL-10 and IL-13, promoting T spiralis expulsion from the host. However, this response damages the host, favouring the parasite survival. In the search for new pharmacological strategies that protect against T spiralis infection, a recent study showed that treatment with resiniferatoxin (RTX) modulates the Th1 cytokines production, reducing muscle parasite burden.

OBJECTIVE

To evaluate the effect of RTX treatment on the Th2 cytokines production, the number of eosinophils, mast cells and the intestinal expulsion of T spiralis.

METHODS

Serum levels of IL-4, IL-10 and IL-13 were quantified by ELISA; the number of eosinophils, mast cells and the adult worms of T spiralis in the small intestine was quantified.

RESULTS

RTX treatment increased serum levels of IL-4, IL-10 and IL-13, and it decreases intestinal eosinophilia, however, favours the mastocytosis, promoting T spiralis intestinal expulsion.

CONCLUSIONS

These findings suggest that RTX is capable to modulate the Th2 immune response, promoting T spiralis expulsion, which contributes to the defence against T spiralis infection, placing the RTX as a potential immunomodulatory drug.

Isoimperatorin reduces the effective dose of dexamethasone in a murine model of asthma by inhibiting mast cell activation

Adverse effects that result from dexamethasone (DEX) use are common and serious in patients with asthma. Therefore, alternative anti-inflammatory treatments are being investigated. Isoimperatorin (ISO), an active natural furocoumarin, possesses multiple pharmacological properties, including an anti-inflammation effect. In this study, investigations were conducted on the effect of ISO on mast cell (MC) activation in vitro and whether ISO could reduce the effective dose of DEX in a mast cell-dependent murine model of asthma in vivo. Calcium imaging was used to assess intracellular Ca²⁺ mobilization. Enzyme-linked immunosorbent assay was used to measure the chemokines release. Western blot analysis was conducted to investigate the underlying pathway. Airway inflammation and hyperresponsiveness (AHR) were examined in an asthma model. ISO inhibited Ca²⁺ flux and MC degranulation via Lyn/PLCγ1/PKC, ERK, and P38 MAPK pathways. In the asthma model, ISO, in combination with DEX, showed an additive inhibitory effect on AHR, inflammation, and the number of activated MCs in the lungs and decreased the levels of interleukin (IL)-4, IL-5, IL-6, IL-13, tumor necrosis factor (TNF)-a, and C-C motif chemokine ligand (CCL)-2 in bronchoalveolar lavage fluid. A combination of DEX and ISO may be appropriate if a decrease in the steroid dose is desired owing to dose-dependent adverse effects.

IL-33 and MRGPRX2-Triggered Activation of Human Skin Mast Cells-Elimination of Receptor Expression on Chronic Exposure, but Reinforced Degranulation on Acute Priming

Clinically relevant exocytosis of mast cell (MC) mediators can be triggered by high-affinity IgE receptor (FcεRI)-aggregation (allergic route) or by the so-called pseudo-allergic pathway elicited via MAS-related G protein-coupled receptor-X2 (MRGPRX2). The latter is activated by drugs and endogenous neuropeptides. We recently reported that FcεRI-triggered degranulation is attenuated when human skin mast cells are chronically exposed to IL-33. Here, we were interested in the regulation of the MRGPRX2-route. Chronic exposure of skin MCs to IL-33 basically eliminated the pseudo-allergic/neurogenic route as a result of massive MRGPRX2 reduction. This downregulation seemed to partially require c-Jun N-terminal Kinase (JNK), but not p38, the two kinases activated by IL-33 in skin MCs. Surprisingly, however, JNK had a positive effect on MRGPRX2 expression in the absence of IL-33. This was evidenced by Accell^®-mediated JNK knockdown and JNK inhibition. In stark contrast to the dampening effect upon prolonged exposure, IL-33 was able to prime for increased degranulation by MRGPRX2 ligands when administered directly before stimulation. This supportive effect depended on p38, but not on JNK activity. Our data reinforce the concept that exposure length dictates whether IL-33 will enhance or attenuate secretion. IL-33 is, thus, the first factor to acutely enhance MRGPRX2-triggered degranulation. Finally, we reveal that p38, rarely associated with MC degranulation, can positively affect exocytosis in a context-dependent manner.

Fusion proteins consisting of Bet v 1 and Phl p 5 form IgE-reactive aggregates with reduced allergenic activity

The cross-linking of effector cell-bound IgE antibodies by allergens induces the release of inflammatory mediators which are responsible for the symptoms of allergy. We demonstrate that a recombinant hybrid molecule consisting of the major birch (Bet v 1) and grass (Phl p 5) pollen allergen exhibited reduced allergenic activity as compared to equimolar mixes of the isolated allergens in basophil activation experiments. The reduced allergenic activity of the hybrid was not due to reduced IgE reactivity as demonstrated by IgE binding experiments using sera from allergic patients. Physicochemical characterization of the hybrid by size exclusion chromatography, dynamic light scattering, negative-stain electron microscopy and circular dichroism showed that the hybrid occurred as folded aggregate whereas the isolated allergens were folded monomeric proteins. IgG antibodies raised in rabbits against epitopes of Bet v 1 and Phl p 5 showed reduced reactivity with the hybrid compared to the monomeric allergens. Our results thus demonstrate that aggregation can induce changes in the conformation of allergens and lead to the reduction of allergenic activity. This is a new mechanism for reducing the allergenic activity of allergens which may be important for modifying allergens to exhibit reduced side effects when used for allergen-specific immunotherapy.

Effect of Dietary Fiber and Metabolites on Mast Cell Activation and Mast Cell-Associated Diseases

Many mast cell-associated diseases, including allergies and asthma, have seen a strong increase in prevalence during the past decades, especially in Western(ized) countries. It has been suggested that a Western diet may contribute to the prevalence and manifestation of allergies and asthma through reduced intake of dietary fiber and the subsequent production of their metabolites. Indeed, dietary fiber and its metabolites have been shown to positively influence the development of immune disorders via changes in microbiota composition and the regulation of B- and T-cell activation. However, the effects of these dietary components on the activation of mast cells, key effector cells of the inflammatory response in allergies and asthma, remain poorly characterized. Due to their location in the gut and vascularized tissues, mast cells are exposed to high concentrations of dietary fiber and/or its metabolites. Here, we provide a focused overview of current findings regarding the direct effects of dietary fiber and its various metabolites on the regulation of mast cell activity and the pathophysiology of mast cell-associated diseases.

Peroxisome proliferator-activated receptor-β/δ modulates mast cell phenotype

The peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) is known to have multiple anti-inflammatory effects, typically observed in endothelial cells, macrophages, T cells and B cells. Despite the fact that mast cells are important mediators of inflammation, to date, the role of PPARβ/δ in mast cells has not been examined. Hence, the present study examined the hypothesis that PPARβ/δ modulates mast cell phenotype. Bone-marrow-derived mast cells (BMMCs) and peritoneal mast cells from Pparβ/δ^+/+ mice expressed higher levels of high-affinity IgE receptor (FcεRI) compared with Pparβ/δ^-/- mice. BMMCs from Pparβ/δ^+/+ mice also exhibited dense granules, associated with higher expression of enzymes and proteases compared with Pparβ/δ^-/- mice. Resting BMMCs from Pparβ/δ^+/+ mice secreted lower levels of inflammatory cytokines, associated with the altered activation of phospholipase Cγ1 and extracellular signal-regulated kinases compared with Pparβ/δ^-/- mice. Moreover, the production of cytokines by mast cells induced by various stimuli was highly dependent on PPARβ/δ expression. This study demonstrates that PPARβ/δ is an important regulator of mast cell phenotype.

Ramalin Isolated from Ramalina Terebrata Attenuates Atopic Dermatitis-like Skin Lesions in Balb/c Mice and Cutaneous Immune Responses in Keratinocytes and Mast Cells

Atopic dermatitis (AD) is a chronic inflammatory skin disease that involves eczematous skin lesions with pruritic erythematous papules. In this study, we investigated the mitigating effects of ramalin, a component of the Antarctic lichen Ramalina terebrata against AD in vivo and in vitro. Oral administration of ramalin lessened scratching behaviors and significantly reduced both serum immunoglobulin E and IL-4 levels, and mRNA levels of IL-4 and IL-10 in AD-induced Balb/c mice. In vitro, treatment with ramalin produced significantly less inflammatory chemokines and cytokines, including TARC, MCP-1, RANTES, and IL-8 in TNF-α-stimulated HaCaT cells. In addition, ramalin inhibited the activation of nuclear factor-kappa B as well as the phosphorylation of mitogen-activated protein kinases (MAPK). Furthermore, ramalin treatment resulted in decreased production of β-hexosaminidase and proinflammatory cytokines IL-4, IL-6, and TNF-α in 2,4 dinitrophenyl-human serum albumin-stimulated RBL-2H3 cells through blocking MAPK signaling pathways. The results suggest that ramalin modulates the production of immune mediators by inhibiting the nuclear factor-kappa B and MAPK signaling pathways. Taken together, ramalin effectively attenuated the development of AD and promoted the mitigating effects on Th2 cell-mediated immune responses and the production of inflammatory mediators in mast cells and keratinocytes. Thus, ramalin may be a potential therapeutic agent for AD. Copyright © 2016 John Wiley & Sons, Ltd.

Tetraspanin CD151 Is a Negative Regulator of FcεRI-Mediated Mast Cell Activation

Mast cells are critical in the pathogenesis of allergic disease due to the release of preformed and newly synthesized mediators, yet the mechanisms controlling mast cell activation are not well understood. Members of the tetraspanin family are recently emerging as modulators of FcεRI-mediated mast cell activation; however, mechanistic understanding of their function is currently lacking. The tetraspanin CD151 is a poorly understood member of this family and is specifically induced on mouse and human mast cells upon FcεRI aggregation but its functional effects are unknown. In this study, we show that CD151 deficiency significantly exacerbates the IgE-mediated late phase inflammation in a murine model of passive cutaneous anaphylaxis. Ex vivo, FcεRI stimulation of bone marrow-derived mast cells from CD151(-/-) mice resulted in significantly enhanced expression of proinflammatory cytokines IL-4, IL-13, and TNF-α compared with wild-type controls. However, FcεRI-induced mast cell degranulation was unaffected. At the molecular signaling level, CD151 selectively regulated IgE-induced activation of ERK1/2 and PI3K, associated with cytokine production, but had no effect on the phospholipase Cγ1 signaling, associated with degranulation. Collectively, our data indicate that CD151 exerts negative regulation over IgE-induced late phase responses and cytokine production in mast cells.

Formoterol synergy with des-ciclesonide inhibits IL-4 expression in IgE/antigen-induced mast cells by inhibiting JNK activation

Inhaled corticosteroid (ICS) therapy in combination with long-acting β-adrenergic agonists (LABA) is the most important treatment for allergic asthma, although the mechanism still remains unclear. However, mast cells play a central role in the pathogenesis of asthma. In this study, we explored the sole or synergetic effects of des-ciclesonide (ICS) and formoterol (LABA) on the cytokines IL-4 and IL-13 and on histamine release from mast cells (RBL-2H3 cells). We found that des-ciclesonide (0.1, 1 and 10nM) and formoterol (0.1, 1 and 10μM) alone attenuated DNP-BSA-induced IL-4 and IL-13 production, respectively, in a concentration-dependent manner in DNP-IgE-sensitized mast cells. Des-ciclesonide (0.2nM) and formoterol (1μM) alone also reduced histamine production. However, the combination of des-ciclesonide (0.2nM) and formoterol (1μM) had a synergistic inhibition effect on IL-4 mRNA expression and protein production but not IL-13 and histamine release. The JNK inhibitor SP600125 (10μM) inhibited antigen-induced mRNA expression and protein production of IL-4. Des-ciclesonide and formoterol alone inhibited the activation of JNK in a concentration-dependent manner, and the combination of des-ciclesonide (0.2nM) and formoterol (1μM) exhibited greater inhibition effect compared with des-ciclesonide (0.2nM) or formoterol (1μM) alone. Taken together, these synergistic effects on mast cells might provide the rationale for the development of the most recent ICS/LABA combination approved for asthma therapy.

Diallyl Disulfide Prevents Cyclophosphamide-Induced Hemorrhagic Cystitis in Rats through the Inhibition of Oxidative Damage, MAPKs, and NF-κB Pathways

This study investigated the possible effects and molecular mechanisms of diallyl disulfide (DADS) against cyclophosphamide (CP)-induced hemorrhagic cystitis (HC) in rats. Inflammation response was assessed by histopathology and serum cytokines levels. We determined the protein expressions of nuclear transcription factor kappa-B (NF-κB), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and tumor necrosis factor-α (TNF-α), oxidative stress, urinary nitrite-nitrate, malondialdehyde (MDA), and 8-hydroxy-2’-deoxyguanosine (8-OHdG). Finally, we studied the involvement of mitogen-activated protein kinases (MAPKs) signaling in the protective effects of DADS against CP-induced HC. CP treatment caused a HC which was evidenced by an increase in histopathological changes, proinflammatory cytokines levels, urinary nitrite-nitrate level, and the protein expression of NF-κB, COX-2, iNOS, TNF-α, p-c-Jun N-terminal kinase (JNK), and p-extracellular signal regulated kinase (ERK). The significant decreases in glutathione content and glutathione-S-transferase and glutathione reductase activities, and the significant increase in MDA content and urinary MDA and 8-OHdG levels indicated that CP-induced bladder injury was mediated through oxidative DNA damage. In contrast, DADS pretreatment attenuated CP-induced HC, including histopathological lesion, serum cytokines levels, oxidative damage, and urinary oxidative DNA damage. DADS also caused significantly decreased the protein expressions of NF-κB, COX-2, iNOS, TNF-α, p-JNK, and p-ERK. These results indicate that DADS prevents CP-induced HC and that the protective effects of DADS may be due to its ability to regulate proinflammatory cytokines production by inhibition of NF-κB and MAPKs expressions, and its potent anti-oxidative capability through reduction of oxidative DNA damage in the bladder.

Cyclical mechanical stretch enhances degranulation and IL-4 secretion in RBL-2H3 mast cells

Mast cells are widely distributed in the body and affect their surrounding environment through degranulation and secretion of cytokines. Conversely, mast cells are influenced by environmental stimuli such as cyclical mechanical stretch (CMS), such as that induced by heartbeat and respiration. Peripherally distributed mast cells are surrounded by extracellular matrix, where they bind IgE on their surface by expressing the high-affinity Fc receptor for IgE (FcεRI), and they release mediators after cross-linking of surface-bound IgE by allergen. To analyse how CMS affects mast cell responses, we examined the effect of applying CMS on the behaviour of IgE-bound mast cells (RBL-2H3 cell line) adhering to fibronectin as a substitute for extracellular matrix. We found that CMS enhanced FcεRI-mediated secretion in the presence of antigen (2,4-dinitrophenol-bovine serum albumin). CMS increased expression of IL-4 mRNA and secretion of IL-4 protein. Western blot analysis showed that CMS changes the signal transduction in mitogen-activated protein kinases and AKT, which in turn alters the regulation of IL-4 and increases the secretion of IL-4. These results suggest that CMS modulates the effect of mast cells on inflammation and resultant tissue remodelling. Understanding how CMS affects mast cell responses is crucial for developing therapies to treat mast cell-related diseases.

Absence of Tec family kinases interleukin-2 inducible T cell kinase (Itk) and Bruton's tyrosine kinase (Btk) severely impairs Fc epsilonRI-dependent mast cell responses

Mast cells are critical effector cells in the pathophysiology of allergic asthma and other IgE-mediated diseases. The Tec family of tyrosine kinases Itk and Btk serve as critical signal amplifiers downstream of antigen receptors. Although both kinases are expressed and activated in mast cells following FcεRI stimulation, their individual contributions are not clear. To determine whether these kinases play unique and/or complementary roles in FcεRI signaling and mast cell function, we generated Itk and Btk double knock-out mice. Analyses of these mice show decreased mast cell granularity and impaired passive systemic anaphylaxis responses. This impaired response is accompanied by a significant elevation in serum IgE in Itk/Btk double knock-out mice. In vitro analyses of bone marrow-derived mast cells (BMMCs) indicated that Itk/Btk double knock-out BMMCs are defective in degranulation and cytokine secretion responses downstream to FcεRI activation. These responses were accompanied by a significant reduction in PLCγ2 phosphorylation and severely impaired calcium responses in these cells. This defect also results in altered NFAT1 nuclear localization in double knock-out BMMCs. Network analysis suggests that although they may share substrates, Itk plays both positive and negative roles, while Btk primarily plays a positive role in mast cell FcεRI-induced cytokine secretion.

Physical interactions between mast cells and eosinophils: a novel mechanism enhancing eosinophil survival in vitro

BACKGROUND

Mast cells (MCs) and eosinophils (Eos) are the key effector cells of the allergic reaction. Although classically associated with different stages of the response, the cells co-exist in the inflamed tissue in the late and chronic phases in high numbers and are likely to cross-talk. While some mediators of MCs are known to affect Eos biology and vice versa, paracrine and physical interplay between the two cells has not been described yet. We aimed to investigate whether intercellular MC-Eos communication could take place in the allergic response and exert functional bidirectional changes on the cells.

METHODS

Tissue sections from various allergic disorders were specifically stained for both cells. Human cord blood-derived MCs and peripheral blood Eos, co-cultured under different conditions, were studied by advanced microscopy and flow cytometry.

RESULTS

Several co-localized MC-Eos pairs were detected in human nasal polyps and asthmatic bronchi, as well in mouse atopic dermatitis. In vitro, MCs and Eos formed stable conjugates at high rates, with clear membrane contact. In the presence of MCs, Eos were significantly more viable under several co-culture conditions and at both IgE-activated and steroid-inhibited settings. MC regulation of Eos survival required communication through soluble mediators but was even more dependent on physical cell-cell contact.

CONCLUSIONS

Our findings provide the first evidence for a complex network of paracrine and membrane interactions between MCs and Eos. The prosurvival phenotype induced by this MC-Eos interplay may be critical for sustaining chronic allergic inflammation.

SOCS3 suppresses the expression of IL-4 cytokine by inhibiting the phosphorylation of c-Jun through the ERK signaling pathway in rat mast cell line RBL-2H3

SOCS3 is well known to negatively regulate various cytokine-mediated signaling responses, but its direct role in the expression of specific cytokines has not been clearly elucidated. To understand the role of SOCS3 in the expression of IL-4, one of the key Th2 cytokines, RBL-2H3 cells (a rat mast cell line) were engineered to express SOCS3 constitutively at a high level or at a lower level using shRNA. In RBL-2H3 cells stably expressing SOCS3, the RNA and protein levels of IL-4 were significantly decreased, while it was opposite in RBL-2H3 cells containing shRNA for SOCS3. Overexpression of SOCS3 was found to reduce the level of calcium ionophore-induced phosphorylation of ERK1/2 and c-Jun transcription factor. Consistent with this data, knockdown of SOCS3 increased the level of phosphorylated ERK1 and ERK2. Taken together, SOCS3 appears to play an important role as a negative feedback inhibitor in the expression of IL-4 by inhibiting serine phosphorylation of c-Jun via the ERK signaling pathway.

The regulatory mechanism of β-eudesmol is through the suppression of caspase-1 activation in mast cell-mediated inflammatory response

β-Eudesmol is sesquiterpenoid alcohol which contains the rhizome of Atractylodes lancea. Although it has multiple pharmacological effects, the anti-inflammatory effect of β-eudesmol and its molecular mechanisms are poorly elucidated. In this study, we investigated the regulatory mechanism of β-eudesmol on mast cell-mediated inflammatory response. The results indicated that β-eudesmol inhibited the production and expression of interleukin (IL)-6 on phorbol 12-myristate 13-acetate and calcium ionophore A23187-stimulated human mast cell (HMC). In activated HMC-1 cells, β-eudesmol suppressed activation of p38 mitogen-activated protein kinase (MAPKs) and nuclear factor-κB. In addition, β-eudesmol suppressed the activation of caspase-1 and expression of receptor-interacting protein-2. These results provide new insights into the pharmacological actions of β-eudesmol as a potential molecule for use in therapy in mast cell-mediated inflammatory diseases.

Losartan prevents sepsis-induced acute lung injury and decreases activation of nuclear factor kappaB and mitogen-activated protein kinases

Lack of specific and efficient therapy leads to the high mortality rate of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Losartan is a potent pharmaceutical drug for ALI/ARDS. However, the protective effects and mechanisms of losartan remain incompletely known. This study evaluates the effects of losartan on ALI/ARDS and further investigates the possible mechanisms of these protective effects. Mice received i.p. injections of the AT1 inhibitor losartan (15 mg/kg), or control vehicle, half hour after cecal ligation and puncture (CLP). Plasma TNF-alpha, IL-1beta, and IL-6 cytokines were assayed 6 h after CLP. Blood gas, wet/dry lung weight ratio, lung tissue histology for occurrence of ALI/ARDS, and survival were examined. Lastly, nuclear factor kappaB (NF-kappaB) activations, IkappaB-alpha degradations, phosphorylations of p38 MAPK, extracellular signal-regulated kinase 1/2, and c-Jun N-terminal kinase expressions were evaluated in lung tissue. Losartan treatment significantly attenuated TNF-alpha, IL-6, and IL-1beta 6 h after CLP. Furthermore, losartan prevented blood gas and histopathologic appearance of ALI/ARDS after sepsis and significantly improved survival. Finally, losartan given after sepsis led to inhibition of lung tissue NF-kappaB activation (P < 0.01 vs. CLP group), attenuated degradation of IkappaB-alpha, and inhibited phosphorylation of p38MAPK, extracellular signal-regulated kinase 1/2, and c-Jun N-terminal kinase, pathways critical for cytokine release. These data reveal that losartan exerts a protective effect on ALI/ARDS, and this protective effect may be dependent, at least in part, on NF-kappaB and MAPK mechanisms.

Selinidin suppresses IgE-mediated mast cell activation by inhibiting multiple steps of Fc epsilonRI signaling

IgE-mediated mast cell activation is critical for development of allergic inflammation. We have recently found that selinidin, one of the coumarin derivatives isolated from Angelica keiskei, attenuates mast cell degranulation following engagement of the high-affinity receptor for IgE (Fc epsilonRI) with IgE and antigen. In the present study, we investigated the effects of selinidin on intracellular signaling and mast cell activation employing bone marrow-derived mast cells. Here, we report that selinidin attenuates the release of beta-hexosaminidase, synthesis of leukotriene C4, and production of tumor necrosis factor-alpha without affecting IgE-Fc epsilonRI binding. Furthermore, biochemical analyses of the Fc epsilonRI-mediated signaling pathway demonstrated that selinidin decreases phosphorylation of phospholipase C-gamma1, p38 mitogen-activated protein kinase, and IkappaB-alpha upon FcepsilonRI stimulation. These results suggest that this compound suppresses IgE-mediated mast cell activation by inhibiting multiple steps of FcepsilonRI-dependent signaling pathways and would be beneficial for the prevention of allergic inflammation.

The mast cell and allergic diseases: role in pathogenesis and implications for therapy

Mast cells have long been recognized for their role in the genesis of allergic inflammation; and more recently for their participation in innate and acquired immune responses. Mast cells reside within tissues including the skin and mucosal membranes, which interface with the external environment; as well as being found within vascularized tissues next to nerves, blood vessels and glandular structures. Mast cells have the capability of reacting both within minutes and over hours to specific stimuli, with local and systemic effects. Mast cells express the high affinity IgE receptor (FcepsilonRI) and upon aggregation of FcepsilonRI by allergen-specific IgE, mast cells release and generate biologically active preformed and newly synthesized mediators which are involved in many aspects of allergic inflammation. While mast cells have been well documented to be essential for acute allergic reactions, more recently the importance of mast cells in reacting through pattern recognition receptors in innate immune responses has become recognized. Moreover, as our molecular understanding of the mast cell has evolved, novel targets for modulation have been identified with promising therapeutic potential.

The regulatory effect of SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-l]benzenesulfonamide) on stem cell factor induced migration of mast cells

SC-236, (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-]benzenesulfonamide; C(16)H(11)ClF(3)N(3)O(2)S), is a highly selective cyclooxygenase (COX)-2 inhibitor. Recently, there have been reports that SC-236 protects against cartilage damage in addition to reducing inflammation and pain in osteoarthritis. However, the mechanism involved in the inflammatory allergic reaction has not been examined. Mast cells accumulation can be related to inflammatory conditions, including allergic rhinitis, asthma, and rheumatoid arthritis. The aim of the present study is to investigate the effects of SC-236 on stem cell factor (SCF)-induced migration, morphological alteration, and cytokine production of rat peritoneal mast cells (RPMCs). We observed that SCF significantly induced the migration and morphological alteration. The ability of SCF to enhance migration and morphological alteration was abolished by treatment with SC-236. In addition, production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and vascular endothelial growth factor (VEGF) production induced by SCF was significantly inhibited by treatment with SC-236. Previous work has demonstrated that SCF-induced migration and cytokine production of mast cells require p38 MAPK activation. We also showed that SC-236 suppresses the SCF-induced p38 MAPK activation in RPMCs. These data suggest that SC-236 inhibits migration and cytokine production through suppression of p38 MAPK activation. These results provided new insight into the pharmacological actions of SC-236 and its potential therapeutic role in the treatment of inflammatory allergic diseases.

GLUTAMINE PREVENTS ACTIVATION OF NF-kappaB AND STRESS KINASE PATHWAYS, ATTENUATES INFLAMMATORY CYTOKINE RELEASE, AND PREVENTS ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS) FOLLOWING SEPSIS

Glutamine (GLN) has been shown to attenuate cytokine release from LPS-stimulated human peripheral blood mononuclear cells; however, the in vivo antiinflammatory effect of GLN in polymicrobial sepsis and ARDS is unknown. This study evaluates the effect of GLN on inflammatory cytokine release and the pathways that may mediate antiinflammatory effects of GLN in the lung. Either 0.75 g/kg of GLN or saline placebo (SP) was administered to male rats 1 h after cecal ligation and puncture (CLP). NF-kappaB activation, IKBalpha degradation, phosphorylation of p38 MAPK, ERK, and MKP-1 expression were evaluated in lung tissue 6 h post-CLP. Lung tissue iNOS and eNOS, TNF-alpha, IL-6, and IL-18 cytokines were assayed. Last, lung histopathology for occurrence of ARDS and survival were examined. GLN given 1 h postsepsis led to inhibition of lung tissue NF-kappaB activation (P < 0.001 vs. SP), attenuated degradation of IKBalpha, and inhibited phosphorylation of p38 MAPK, and ERK, pathways critical for cytokine release. GLN treatment increased MKP-1 peptide expression and significantly attenuated TNF-alpha and IL-6 6 h after CLP. IL-18 was attenuated by GLN at multiple time points post-CLP. Further, GLN abrogated increases in lung iNOS expression and enhanced lung eNOS postsepsis. Finally, GLN prevented the histopathologic appearance of ARDS after sepsis and significantly improved survival. These data reveal that GLN exerts an antiinflammatory effect in sepsis that may be mediated via attenuation of multiple pathways of inflammation such as NF-kappaB, p38 MAPK, ERK, and MKP-1. GLN also showed an inhibition of increases in iNOS expression. The antiinflammatory effect of GLN was associated with attenuation of ARDS and mortality.

Sopoongsan Inhibits Mast Cell-Mediated Anaphylactic Reactions and Inflammatory Cytokine Secretion

BACKGROUND

Mast cells are key effector cells in the early-phase allergic inflammation and in diverse immunological and pathological processes. Sopoongsan (SPS), a traditional Korean medicine, has been used as therapeutics for allergic diseases such as atopic dermatitis (AD). The precise effect in experimental models of SPS, however, remains unknown. In this report, we investigated the effect of SPS on mast cell-mediated anaphylactic reactions and cytokine production in in vivo and in vitro murine models.

METHODS

Compound 48/80-induced histamine and ear swelling were measured with the various concentrations of SPS. The amount of dye was determined colorimetrically after antidinitrophenyl IgE antibody-induced passive cutaneous anaphylaxis reaction. Secretion of tumor necrosis factor-alpha (TNF-alpha), interleukin-8 (IL-8) and IL-6 in supernatants from HMC-1 cells was measured by a sandwich enzyme-linked immunosorbent assay. The expression level of nuclear factor (NF)-kappaB/Rel A in the nucleus and the activation of mitogen-activated protein kinases (MAPKs) were examined by Western blot analysis.

RESULTS

SPS inhibited the degranulation and histamine release from the rat peritoneal mast cells activated by compound 48/80. Compound 48/80-induced ear swelling was significantly reduced. SPS also showed an inhibitory effect of passive cutaneous anaphylaxis reaction. Significantly reduced levels (p < 0.05) of TNF-alpha, IL-8 and IL-6 were observed in the human mast cell line with SPS and SPS components. In addition, SPS inhibited an increase of NF-kappaB and extracellular signal-regulated kinase 1/2 activity.

CONCLUSIONS

These findings suggest that SPS has an inhibitory effect on atopic allergic reaction and this might be useful for the clinical application to treat allergic diseases such as AD.

Tumour necrosis factor (TNFalpha) as a novel therapeutic target in symptomatic corticosteroid dependent asthma

BACKGROUND

Tumour necrosis factor alpha (TNFalpha) is a major therapeutic target in a range of chronic inflammatory disorders characterised by a Th1 type immune response in which TNFalpha is generated in excess. By contrast, asthma is regarded as a Th2 type disorder, especially when associated with atopy. However, as asthma becomes more severe and chronic, it adopts additional characteristics including corticosteroid refractoriness and involvement of neutrophils suggestive of an altered inflammatory profile towards a Th1 type response, incriminating cytokines such as TNFalpha.

METHODS

TNFalpha levels in bronchoalveolar lavage (BAL) fluid of 26 healthy controls, 42 subjects with mild asthma and 20 with severe asthma were measured by immunoassay, and TNFalpha gene expression was determined in endobronchial biopsy specimens from 14 patients with mild asthma and 14 with severe asthma. The cellular localisation of TNFalpha was assessed by immunohistochemistry. An open label uncontrolled clinical study was then undertaken in 17 subjects with severe asthma to evaluate the effect of 12 weeks of treatment with the soluble TNFalpha receptor-IgG1Fc fusion protein, etanercept.

RESULTS

TNFalpha levels in BAL fluid, TNFalpha gene expression and TNFalpha immunoreative cells were increased in subjects with severe corticosteroid dependent asthma. Etanercept treatment was associated with improvement in asthma symptoms, lung function, and bronchial hyperresponsiveness.

CONCLUSIONS

These findings may be of clinical significance in identifying TNFalpha as a new therapeutic target in subjects with severe asthma. The effects of anti-TNF treatment now require confirmation in placebo controlled studies.

Cyclooxygenase-2 inhibitor SC-236 [4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-l] benzenesulfonamide] suppresses nuclear factor-kappaB activation and phosphorylation of p38 mitogen-activated protein kinase, extracellular signal-regulated kinase, and c-Jun N-terminal kinase in human mast cell line cells

SC-236 [4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-l] benzenesulfonamide; C16H11ClF3N3O2S] is a highly selective cyclooxygenase (COX)-2 inhibitor. However, the exact mechanism that accounts for the anti-inflammatory effect of SC-236 is not completely understood. The aim of the present study was to elucidate whether and how SC-236 modulates the inflammatory reaction in a stimulated human mast cell (HMC) line, HMC-1. SC-236 inhibited the expression of tumor necrosis factor-alpha, interleukin (IL)-6, IL-8, vascular endothelial growth factor, COX-2, inducible nitric-oxide synthase, and hypoxia-inducible factor-1alpha in phorbol 12-myristate 13-acetate plus calcium ionophore A23187 (PMACI)-stimulated HMC-1. SC-236 suppressed nuclear factor (NF)-kappaB activation induced by PMACI, leading to suppression of IkappaB-alpha phosphorylation and degradation. SC-236 also suppressed strong induction of NF-kappaB promoter-mediated luciferase activity. In addition, SC-236 suppressed PMACI-induced phosphorylation of the mitogen-activated protein kinase p38, the extracellular-regulated kinase p44, and the c-Jun N-terminal kinase and induced expression of mitogen-activated protein kinase phosphatase-1. These results provide new insight into the pharmacological actions of SC-236 as a potential molecule for therapy of mast cell-mediated inflammatory diseases.

Nitric Oxide Inhibits IgE-Dependent Cytokine Production and Fos and Jun Activation in Mast Cells

NO is a cell-derived radical reported to inhibit mast cell degranulation and subsequent allergic inflammation, although whether its action is nonspecific or occurs via specific molecular mechanisms remains unknown. To examine this question, we set out to determine whether NO inhibits mast cell cytokine production, and, if so, whether it also alters FcepsilonRI-dependent signal transduction. As hypothesized, the radical inhibited IgE/Ag-induced IL-4, IL-6, and TNF production. Although NO did not influence phosphorylated JNK, p38 MAPK, or p44/42 MAPK, it did inhibit phosphorylation of phospholipase Cgamma1 and the AP-1 transcription factor protein c-Jun, but not NF-kappaB or CREB. NO further completely abrogated IgE/Ag-induced DNA-binding activity of the nuclear AP-1 proteins Fos and Jun. These results show that NO is capable of inhibiting FcepsilonRI-dependent mast cell cytokine production at the level of gene regulation, and suggest too that NO may contribute to resolution of allergic inflammation.