Ion channels regulating mast cell biology

Chloride channels and mast cell function: pioneering new frontiers in IBD therapy

Emerging evidence indicates that chloride channels (ClCs) significantly affect the pathogenesis of inflammatory bowel disease (IBD) through their regulatory roles in mast cell function and epithelial integrity. IBD, encompassing conditions such as Crohn's disease and ulcerative colitis, involves chronic inflammation of the gastrointestinal tract, where channels influence immune responses, fluid balance, and cellular signalling pathways essential for maintaining mucosal homeostasis. This review examines the specific roles of ClC in mast cells, focussing on the regulation of mast cell activation, degranulation, cytokine release, and immune cell recruitment in inflamed tissues. Key channels, including Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and ClC-2, are discussed in detail because of their involvement in maintaining intestinal epithelial barrier function, a critical factor disrupted in IBD. For example, CFTR facilitates chloride ion transport across epithelial cells, which is essential for mucosal hydration and maintenance of the intestinal barrier. Reduced CFTR function can compromise this barrier, permitting microbial antigens to penetrate the underlying tissues and triggering excessive immune responses. ClC-2, another chloride channel expressed in mast cells and epithelial cells, supports tight junction integrity, contributes to barrier function, and reduces intestinal permeability. Dysregulation of these channels is linked to altered mast cell activity and excessive release of pro-inflammatory mediators, exacerbating IBD symptoms, such as diarrhoea, abdominal pain, and tissue damage. Here, we review recent pharmacological strategies targeting ClC, including CFTR potentiators and ClC-2 activators, which show the potential to mitigate inflammatory responses. Additionally, experimental approaches for selective modulation of chloride channels in mast cells have been explored. Although targeting ClC offers promising therapeutic avenues, challenges remain in achieving specificity and minimizing side effects. This review highlights the therapeutic potential of Cl channel modulation in mast cells as a novel approach for IBD treatment, aiming to reduce inflammation and restore intestinal homeostasis in affected patients.

The impact of atmospheric ultrafine particulate matter on IgE-mediated type 1 hypersensitivity reaction

The effect of atmospheric ultrafine particulate matter (UPM) on respiratory allergic diseases has been investigated for decades; however, the precise molecular mechanisms underlying these effects remain poorly understood. In this study, we used a simulated UPM (sUPM) generated via the spark discharge method to refine black carbon, a core particle that closely mimics real-world UPM, including the size (i.e., size of agglomerates: 165 nm) and organic carbon/elemental carbon ratio (i.e., 2.62). When 25 μg/mouse of dispersed sUPM was instilled into the lungs of mice, it promoted the infiltration and degranulation response of pulmonary mast cells, and exposure to sUPM in an immunoglobulin E (IgE)-mediated passive anaphylaxis model intensified the degranulation response of peripheral mast cells. These effects of sUPM were demonstrated to amplify the downstream signaling mechanism of the high-affinity IgE receptor (FcεRI) mediated by IgE when tested using rat basophil leukemia (RBL)-2H3 and mouse bone marrow-derived mast cells (BMMCs) collected from the bone marrow of BALB/c mice. These results indicate that airborne UPM can exacerbate type 1 hypersensitivity reactions by enhancing the IgE-mediated signaling pathways within mast cells. Furthermore, this study provided mechanistic evidence on exacerbated allergic pulmonary diseases induced by UPM inhalation.

Exploring potential ion channel targets for rheumatoid arthritis: combination of network analysis and gene expression analysis

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation of the synovial membrane that leads to the destruction of cartilage and bone. Currently, pharmacological targeting of ion channels is being increasingly recognized as an attractive and feasible strategy for the treatment of RA. The present work employs a network analysis approach to predict the most promising ion channel target for potential RA-treating drugs. A protein-protein interaction map was generated for 343 genes associated with inflammation in RA and ion channel genes using Search Tool for the Retrieval of Interacting Genes and visualized using Cytoscape. Based on the betweenness centrality and traffic values as key topological parameters, 17 hub nodes were identified, including FOS (9800.85), tumor necrosis factor (3654.60), TGFB1 (3305.75), and VEGFA (3052.88). The backbone network constructed with these 17 hub genes was intensely analyzed to identify the most promising ion channel target using network analyzer. Calcium permeating ion channels, especially store-operated calcium entry channels, and their associated regulatory proteins were found to highly interact with RA inflammatory hub genes. This significant ion channel target for RA identified by theoretical and statistical studies was further validated by a pilot case-control gene expression study. Experimental verification of the above findings in 75 RA cases and 25 controls showed increased ORAI1 expression. Thus, with a combination of network analysis approach and gene expression studies, we have explored potential targets for RA treatment.

Depression of CaV1.2 activation and expression in mast cells ameliorates allergic inflammation diseases

Allergic inflammation is closely related to the activation of mast cells (MCs), which is regulated by its intracellular Ca2+ level, but the intake and effects of the intracellular Ca2+ remain unclear. The Ca2+ influx is controlled by members of Ca2+ channels, among which calcium voltage-gated channel subunit alpha1 C (CaV1.2) is the most robust. This study aimed to reveal the role and underlying mechanism of MC CaV1.2 in allergic inflammation. We found that CaV1.2 participated in MC activation and allergic inflammation. Nimodipine (Nim), as a strong CaV1.2-specific antagonist, ameliorated allergic inflammation in mice. Further, CaV1.2 activation in MC was triggered by phosphatizing at its Ser1928 through protein kinase C (PKC), which calcium/calmodulin-dependent protein kinase II (CaMKII) catalyzed. Overexpression or knockdown of MC CaV1.2 influenced MC activation. Importantly, CaV1.2 expression in MC had detrimental effects, while its deficiency ameliorated allergic pulmonary inflammation. Results provide novel insights into CaV1.2 function and a potential drug target for controlling allergic inflammation.

Can Electrical Stimulation Prevent Recurrence of Keloid Scars? A Scoping Review

Objective: Keloids represent a symptomatic, aberrant healing process that is difficult to treat with high recurrence rates spanning from 55% to 100% if treated via excision without adjuvant therapy. Electrical stimulation (ES) has demonstrated findings that suggest it could reduce the recurrence rate of keloids after resection. Therefore, the aim of this study is to conduct a scoping review to investigate ES as an adjuvant therapy for decreasing keloid recurrence after excision. Approach: A scoping review was performed using PubMed and Web of Science databases. The search strategy encompassed terms linking keloids and various aspects of electrical stimulation. Results: Our search yielded 2,229 articles, of which 115 articles were analyzed as full text and 1 article met inclusion criteria. Despite this, ES has demonstrated other evidence that suggests its utility. ES has been shown to counter keloidic features by reducing mast cell counts, shifting wound composition from M2 to M1 macrophages, promoting angiogenesis, and controlling fibroblast orientation and location. An alternating current will orient fibroblasts perpendicular to the current without unintended migration. Innovation: Our study indicates that, based on a compilation of clinical and preclinical in vitro data, the optimal scenario for ES in the role of keloid treatment is after excision with a biphasic pulsed application and square waveform. Conclusions: ES could serve as a multifaceted, adjuvant treatment after keloid excision, steering the healing process away from keloid-associated characteristics. Its cost-effectiveness means it could be adopted globally, providing a strategy to mitigate the burden of keloids irrespective of other available treatments or economic conditions.

New anticonvulsant candidates prevent P-glycoprotein (P-gp) overexpression in a pharmacoresistant seizure model in mice

Despite the approval of a considerable number of last generation antiepileptic drugs (AEDs) (only in the last decade, six drugs have gained Food and Drug Administration approval), the global figures of seizure control have seemingly not improved, and available AED can still be regarded as symptomatic treatments. Fresh thinking in AEDs drug discovery, including the development of drugs with novel mechanisms of action, is required to achieve truly innovative antiepileptic medications. The transporter hypothesis proposes that inadequate penetration of AEDs across the blood-brain barrier, caused by increased expression of efflux transporters such as P-glycoprotein (P-gp), contributes to drug-resistant epilepsy. Neuroinflammation due to high levels of glutamate has been identified as one of the causes of P-gp upregulation, and several studies in animal models of epilepsy suggest that antiinflammatory drugs might prevent P-gp overexpression and, thus, avoid the development of refractory epilepsy. We have applied ligand-based in silico screening to select compounds that exert dual anticonvulsant and antiinflammatory effects. Five of the hits were tested in animal models of seizure, with protective effects. Later, two of them (sebacic acid (SA) and gamma-decanolactone) were submitted to the recently described MP23 model of drug-resistant seizures. All in all, SA displayed the best profile, showing activity in the maximal electroshock seizure (MES) and pentylenetetrazol (PTZ) seizure models, and reversing resistance to phenytoin (PHT) and decreasing the P-gp upregulation in the MP23 model. Furthermore, pretreatment with SA in the pilocarpine status epilepticus (SE) model resulted in decreased histamine release in comparison with nontreated animals. This is the first report of the use of the MP23 model to screen for novel anticonvulsant compounds that may avoid the development of P-gp-related drug resistance.

Defining the role of CFTR channel blocker and ClC-2 activator in DNBS induced gastrointestinal inflammation

In the present study, we have investigated and/or compared the role of glibenclamide, G as cystic fibrosis transmembrane conductance regulator (CFTR) inhibitor, and lubiprostone, L as chloride channel-2 (ClC-2) activator in the 2,4-dinitrobenzene sulfonic acid (DNBS)-induced gastrointestinal inflammation. GI inflammation was induced by intrarectal administration of DNBS. Rats were randomly allocated in 5 groups as sham control, distilled water + DNBS, sulfasalazine (S) + DNBS, G + DNBS, and L + DNBS. All the groups were pre-treated successively for five days before the induction of colitis. One day before and the first four days after DNBS administration various parameters were studied. Later, blood chemistry, colon’s gross structure, histology, and the antioxidant load was examined. Pre-treatment with G significantly protected the change induced by DNBS concerning the change in body weight, food intake, diarrhea, occult blood in the feces, wet weight of the colon, and spleen. G because of its anti-inflammatory property down-regulated the neutrophil and WBC count and up-regulated the lymphocyte number. Moreover, G efficiently ameliorates the oxidative stress in the colon and declines the level of myeloperoxidase and malondialdehyde and up-regulated the level of superoxide dismutase and glutathione. Lubiprostone has not shown any promising effects, in fact, it causes an increase in diarrheal frequency. Our findings from this study represent that G has good potential to ameliorate GI inflammation induced by DNBS by its multiple actions including CFTR blockage and reducing the release of inflammatory markers from the MCs, anti-inflammatory and free radical scavenging property.

In vitro exposure to Hymenoptera venom and constituents activates discrete ionotropic pathways in mast cells

Calcium entry is central to the functional processes in mast cells and basophils that contribute to the induction and maintenance of inflammatory responses. Mast cells and basophils express an array of calcium channels, which mediate responses to diverse stimuli triggered by small bioactive molecules, physicochemical stimuli and immunological inputs including antigens and direct immune cell interactions. These cells are also highly responsive to certain venoms (such as Hymenoptera envenomations), which cause histamine secretion, cytokine release and an array of pro-inflammatory functional responses. There are gaps in our understanding of the coupling of venom exposure to specific signaling pathways such as activation of calcium channels. In the present study, we performed a current survey of a model mast cell line selected for its pleiotropic responsiveness to multiple pro-inflammatory inputs. As a heterogenous stimulus, Hymenoptera venom activates multiple classes of conductance at the population level but tend to lead to the measurement of only one type of conductance per cell, despite the cell co-expressing multiple channel types. The data show that I_CRAC, I_ARC, and TRPV-like currents are present in the model mast cell populations and respond to venom exposure. We further assessed individual venom components, specifically secretagogues and arachidonic acid, and identified the conductances associated with these stimuli in mast cells. Single-cell calcium assays and immunofluorescence analysis show that there is heterogeneity of channel expression across the cell population, but this heterogeneity does not explain the apparent selectivity for specific channels in response to exposure to venom as a composite stimulus.

The Effect of Statins through Mast Cells in the Pathophysiology of Atherosclerosis: a Review

PURPOSE OF REVIEW

In this review, we discuss the evidence supporting the effects of statins on mast cells (MCs) in atherosclerosis and their molecular mechanism of action.

RECENT FINDINGS

Statins or HMG-CoA reductase inhibitors are known for their lipid-lowering properties and are widely used in the prevention and treatment of cardiovascular diseases. There is growing evidence that statins have an inhibitory effect on MCs, which contributes to the pleiotropic effect of statins in various diseases. MCs are one of the crucial effectors of the immune system which play an essential role in the pathogenesis of multiple disorders. Recent studies have shown that MCs are involved in the development of atherosclerotic plaques. MCs secrete various inflammatory cytokines (IL-6, IL4, TNF-α, and IFNγ) and inflammatory mediators (histamine, tryptase, proteoglycans) after activation by various stimulants. This, in turn, will exacerbate atherosclerosis. Statins suppress the activation of MCs via IgE inhibition which leads to inhibition of inflammatory mediators and cytokines which are involved in the development and progression of atherosclerosis. In keeping with this evidence presented here, MCs can be considered as one of the therapeutic targets for statins in the treatment of atherosclerosis.

Multilayered injection of calcium hydroxylapatite filler on ischial soft tissue to rejuvenate the previous phase of chronic sitting pressure sore

Introduction

During a sitting position, the pressure distribution is located below the ischial tuberosity. Many women have skin atrophy on the ischial area. To treat atrophic changes on the skin above the ischium, volumization and improving skin texture are acquired simultaneously. Two methods of automatic and manual injections using a hard filler with a stitmulating effect were administered respectively to both the dermis and subdermis layers. A biopsy study using various straining evaluated histological tissue reactions after the filler injections.

Methods

This study focused on rejuvenating soft tissue on the atrophic ischeal areas, as described by the author as the previous phase of chronic sitting pressure sore, by using the multi-layered injection of calcium-hydroxylapatite (CaHA) filler. Sixteen women (mean, 38.5 years) were treated from 2012 January to 2019 April. Prior to the injection, 1.5cc of Radiesse^® (calcium hydroxylapatite filler; Merz, Germany) was diluted with 1cc of normal saline and 0.5cc of lidocaine, and 3cc of filler mixture (1:1 dilution) was made. All subjects received the intradermal injection and multi layered subdermal injection with 2.5cc of diluted CaHA filler. A second session for booster treatment was performed at 6 months using the same method. Photography was taken by a camera and a dermascope observation before and 7 months after. Before and 7 months after the first injection, soft tissue depression, skin discoloration, and roughness were assessed. Standard deviations and coefficients of variation were also calculated for changes in depression, discoloration and roughness after the treatment. Biopsy specimens (3×5 mm) were taken from three patients 7 months after the first session. The specimens were analyzed using various stainins.

Results

The improvements of skin quality, skin fold, and roughness were visible at physical examination, medical photography and also at high-resolution dermascope examination in all patients. Post-treatment the depressed amounts on the ischial areas reduced with increased volume.

Conclusion

Depressed soft tissue and skin folds on ischial areas were significantly improved by volumization of subdermal filler injection. The skin quality, roughness, and pigmentation on ischial areas improved, and these improvements may be caused by intradermal micro-droplet injections of CaHA filler which may be influenced by neocollagenesis by numerous fibroblasts and increased micro-blood circulation (neovascularization). This is the first article to show the scientific evidence of neocollagenesis and tissue reaction after an injection of CaHA filler in the dermis, especially using various histological staining and to show various stages of inflammation and foreign body reaction around CaHA particles. Numerous fibroblasts were present around CaHA particles, but plasma cells were not found. Interestingly a few eosinophils were found around CaHA filler. After a significant period of time, multi-layered injections of diluted CaHA tightened and remodeled atrophic ischial skin. The multi layered injection approach was safe and effectively treated ischial soft tissue atrophy without significant side effects, such as infection or delayed swelling or lumps.

Co-Stimulation of Purinergic P2X4 and Prostanoid EP3 Receptors Triggers Synergistic Degranulation in Murine Mast Cells

Mast cells (MCs) recognize antigens (Ag) via IgE-bound high affinity IgE receptors (FcεRI) and trigger type I allergic reactions. FcεRI-mediated MC activation is regulated by various G protein-coupled receptor (GPCR) agonists. We recently reported that ionotropic P2X4 receptor (P2X4R) stimulation enhanced FcεRI-mediated degranulation. Since MCs are involved in Ag-independent hypersensitivity, we investigated whether co-stimulation with ATP and GPCR agonists in the absence of Ag affects MC degranulation. Prostaglandin E2 (PGE2) induced synergistic degranulation when bone marrow-derived MCs (BMMCs) were co-stimulated with ATP, while pharmacological analyses revealed that the effects of PGE2 and ATP were mediated by EP3 and P2X4R, respectively. Consistently, this response was absent in BMMCs prepared from P2X4R-deficient mice. The effects of ATP and PGE2 were reduced by PI3 kinase inhibitors but were insensitive to tyrosine kinase inhibitors which suppressed the enhanced degranulation induced by Ag and ATP. MC-dependent PGE2-triggered vascular hyperpermeability was abrogated in a P2X4R-deficient mouse ear edema model. Collectively, our results suggest that P2X4R signaling enhances EP3R-mediated MC activation via a different mechanism to that involved in enhancing Ag-induced responses. Moreover, the cooperative effects of the common inflammatory mediators ATP and PGE2 on MCs may be involved in Ag-independent hypersensitivity in vivo.

Calcium release-activated calcium modulator 1 as a therapeutic target in allergic skin diseases

Allergic skin disease is the most common skin condition, and considerably affects patients' life quality because of its recurrence and pruritus. Numbers of studies point out that immune cells, including mast cells and T cells, play pathogenic roles in allergic skin diseases, and share similarities in the activation and secretion of cytokines. Calcium Release-Activated Calcium Modulator 1(CRACM1/ORAI1) is a subtype of Ca²⁺ membrane channel, causing Ca²⁺ influx into the cells. As a second messenger, Ca²⁺ is an essential element that regulates immune responses, especially in the development and function of T and B cells. Thus, ORAI1 is considered to participate in allergic diseases. However, the specific mechanism of ORAI1 in skin disorders is still unclear. In order to investigate the roles of ORAI1 in allergic skin disorders, we reviewed the related articles and concluded that ORAI1 could be a potential therapeutic target for allergic skin diseases.

Sodium cromoglycate reduces short- and long-term consequences of status epilepticus in rats

Several studies indicate that sodium cromoglycate (CG) induces neuroprotective effects in acute neurological conditions. The present study focused on investigating if the use of CG in rats during the post-status epilepticus (post-SE) period reduces the acute and long-term consequences of seizure activity. Our results revealed that animals that received a single dose of CG (50 mg/kg s.c.: subcutaneously) during the post-SE period showed a lower number of neurons in the process of dying in the dentate gyrus, hilus, cornu ammonis 1 (CA1), and CA3 of the dorsal hippocampus than the rats that received the vehicle. However, this effect was not evident in layers V-VI of the sensorimotor cortex or the lateral-posterior thalamic nucleus. A second experiment showed that animals that received CG subchronically (50 mg/kg s.c. every 12 h for 5 days followed by 24 mg/kg/day s.c. for 14 days using osmotic minipumps) after SE presented fewer generalized convulsive seizures and less neuronal damage in the lateral-posterior thalamic nucleus but not in the hippocampus or cortex. Our data indicate that CG can be used as a therapeutic strategy to reduce short- and long-term neuronal damage in the hippocampus and thalamus, respectively. The data also indicate that CG can reduce the expression of generalized convulsive spontaneous seizures when it is given during the latent period of epileptogenesis.

Expression and modulation of S100A4 protein by human mast cells

S100A4 protein is expressed in fibroblasts during tissue remodelling and in cancer stem cells and it induces the metastatic spread of tumor cells. In mast cells (MCs) S100A4 have been found in some pathological conditions, but its function in normal MCs remains to be described. The purpose of this study was to characterize the cellular localization of the S100A4 protein in MCs of human tissues with inflammatory or tumor disorders and, to determine the consequence of reducing its expression in MC response. We found that tissue resident MCs stained positive to S100A4. Both human HMC-1 cell line and resting CD34⁺-derived MCs expressed S100A4, whose levels were differentially modulated upon MC activation. Downregulation of the S100A4 protein resulted in MC growth inhibition, enhanced apoptosis and deregulation of MMP-1 and MMP-10 production. Our results suggest that S100A4 is also playing a role in the MC life cycle and functions.

Jacareubin inhibits FcεRI-induced extracellular calcium entry and production of reactive oxygen species required for anaphylactic degranulation of mast cells

Mast cells (MCs) are important effectors in allergic reactions since they produce a number of pre-formed and de novo synthesized pro-inflammatory compounds in response to the high affinity IgE receptor (FcεRI) crosslinking. IgE/Antigen-dependent degranulation and cytokine synthesis in MCs have been recognized as relevant pharmacological targets for the control of deleterious inflammatory reactions. Despite the relevance of allergic diseases worldwide, efficient pharmacological control of mast cell degranulation has been elusive. In this work, the xanthone jacareubin was isolated from the heartwood of the tropical tree Callophyllum brasilense, and its tridimensional structure was determined for the first time by X-ray diffraction. Also, its effects on the main activation parameters of bone marrow-derived mast cells (BMMCs) were evaluated. Jacareubin inhibited IgE/Ag-induced degranulation in a dose-response manner with an IC₅₀ = 46 nM. It also blocked extracellular calcium influx triggered by IgE/Ag complexes and by the SERCA ATPase inhibitor thapsigargin (Thap). Inhibition of calcium entry correlated with a blockage on the reactive oxygen species (ROS) accumulation. Antioxidant capacity of jacareubin was higher than the showed by α-tocopherol and caffeic acid, but similar to trolox. Jacareubin shown inhibitory actions on xanthine oxidase, but not on NADPH oxidase (NOX) activities. In vivo, jacareubin inhibited passive anaphylactic reactions and TPA-induced edema in mice. Our data demonstrate that jacareubin is a potent natural compound able to inhibit anaphylactic degranualtion in mast cells by blunting FcεRI-induced calcium flux needed for secretion of granule content, and suggest that xanthones could be efficient anti-oxidant, antiallergic, and antiinflammatory molecules.

Teriparatide Treatment Improves Bone Defect Healing Via Anabolic Effects on New Bone Formation and Non-Anabolic Effects on Inhibition of Mast Cells in a Murine Cranial Window Model

Investigations of teriparatide (recombinant parathyroid hormone [rPTH]) as a potential treatment for critical defects have demonstrated the predicted anabolic effects on bone formation, and significant non-anabolic effects on healing via undefined mechanisms. Specifically, studies in murine models of structural allograft healing demonstrated that rPTH treatment increased angiogenesis (vessels <30 μm), and decreased arteriogenesis (>30 μm) and mast cell numbers, which lead to decreased fibrosis and accelerated healing. To better understand these non-anabolic effects, we interrogated osteogenesis, vasculogenesis, and mast cell accumulation in mice randomized to placebo (saline), rPTH (20 μg/kg/2 days), or the mast cell inhibitor sodium cromolyn (SC) (24 μg/kg/ 2days), via longitudinal micro-computed tomography (μCT) and multiphoton laser scanning microscopy (MPLSM), in a critical calvaria defect model. μCT demonstrated that SC significantly increased defect window closure and new bone volume versus placebo (p < 0.05), although these effects were not as great as rPTH. Interestingly, both rPTH and SC have similar inhibitory effects on arteriogenesis versus placebo (p < 0.05) without affecting total vascular volume. MPLSM time-course studies in untreated mice revealed that large numbers of mast cells were detected 1 day postoperation (43 ± 17), peaked at 6 days (76 ± 6), and were still present in the critical defect at the end of the experiment on day 30 (20 ± 12). In contrast, angiogenesis was not observed until day 4, and functional vessels were first observed on 6 days, demonstrating that mast cell accumulation precedes vasculogenesis. To confirm a direct role of mast cells on osteogenesis and vasculogenesis, we demonstrated that specific diphtheria toxin-α deletion in Mcpt5-Cre-iDTR mice results in similar affects as SC treatment in WT mice. Collectively, these findings demonstrate that mast cells inhibit bone defect healing by stimulating arteriogenesis associated with fibrotic scaring, and that an efficacious non-anabolic effect of rPTH therapy on bone repair is suppression of arteriogenesis and fibrosis secondary to mast cell inhibition. © 2017 American Society for Bone and Mineral Research.

Considerations in repetitive activation of light sensitive ion channels for long-term studies: Channel rhodopsin in the Drosophila model

Optogenetics is a technique used in various animal models and holds a potential for therapeutic possibilities in mammals. There are technical issues with the use of light sensitive ion channels: reproducible effects over time, controlling where the non-native proteins are targeted within the cell and changes in the biophysical properties of the cells they are expressed in. We used a variant of channel rhodopsin (ChR2-XXL) and targeted expression in neurons of larval Drosophila to investigate the acute and chronic activation, with light pulses, of the channels on synaptic function. The rhodopsin channel modifier all trans retinal (ATR) also plays a role in the sensitivity of the channel to light. Periods of acute, repetitive, and pulsatile blue light exposure over larval development produced attenuated responses. These blue light sensitive ion channels, with ATR, show accommodation and produce an electrical refractory period in inducing synaptic responses. The biological significance and aim of this study is to demonstrate that in controlling particular neurons or neuronal circuits with optogenetics, over time and throughout development, one will have to understand the dynamic nature of activating and silencing the light sensitive channels as well as the biophysical effects on neuronal activity.

Multifactorial Modulation of Food-Induced Anaphylaxis

Prevalence of food-induced anaphylaxis increases progressively and occurs in an unpredictable manner, seriously affecting the quality of life of patients. Intrinsic factors including age, physiological, and genetic features of the patient as well as extrinsic factors such as the intake of drugs and exposure to environmental agents modulate this disorder. It has been proven that diseases, such as mastocytosis, defects in HLA, or filaggrin genes, increase the risk of severe allergic episodes. Certain allergen families such as storage proteins, lipid transfer proteins, or parvalbumins have also been linked to anaphylaxis. Environmental factors such as inhaled allergens or sensitization through the skin can exacerbate or trigger acute anaphylaxis. Moreover, the effect of dietary habits such as the early introduction of certain foods in the diet, and the advantage of the breastfeeding remain as yet unresolved. Interaction of allergens with the intestinal cell barrier together with a set of effector cells represents the primary pathways of food-induced anaphylaxis. After an antigen cross-links the IgEs on the membrane of effector cells, a complex intracellular signaling cascade is initiated, which leads cells to release preformed mediators stored in their granules that are responsible for the acute symptoms of anaphylaxis. Afterward, they can also rapidly synthesize lipid compounds such as prostaglandins or leukotrienes. Cytokines or chemokines are also released, leading to the recruitment and activation of immune cells in the inflammatory microenvironment. Multiple factors that affect food-induced anaphylaxis are discussed in this review, paying special attention to dietary habits and environmental and genetic conditions.

The antinociception of oxytocin on colonic hypersensitivity in rats was mediated by inhibition of mast cell degranulation via Ca(2+)-NOS pathway

This study was conducted to investigate the effects of oxytocin (OT) on visceral hypersensitivity/pain and mast cell degranulation and the underlying mechanisms. We found that oxytocin receptor (OTR) was expressed in colonic mast cells in humans and rats, as well as in human mast cell line-1 (HMC-1), rat basophilic leukemia cell line (RBL-2H3) and mouse mastocytoma cell line (P815). OT decreased 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced visceral hypersensitivity, colonic mast cell degranulation and histamine release after mast cell degranulation in rats. Also, OT attenuated the compound 48/80 (C48/80)-evoked histamine release in P815 cells and inward currents, responsible for the mast cell degranulation, in HMC-1, RBL-2H3 and P815 cells. Moreover, these protective effects of OT against visceral hypersensitivity and mast cell degranulation were eliminated by coadministration of OTR antagonist atosiban or a nonselective inhibitor of nitric oxide synthase (NOS), NG-Methyl-L-arginine acetate salt (L-NMMA). Notably, OT evoked a concentration-dependent increase of intracellular Ca(2+) in HMC-1, RBL-2H3 and P815 cells, which was responsible for the activation of neuronal NOS (NOS1) and endothelial NOS (NOS3). Our findings strongly suggest that OT might exert the antinociception on colonic hypersensitivity through inhibition of mast cell degranulation via Ca(2+)-NOS pathway.

Usefulness of targeting lymphocyte Kv1.3-channels in the treatment of respiratory diseases

T lymphocytes predominantly express delayed rectifier K(+)-channels (Kv1.3) in their plasma membranes. Patch-clamp studies revealed that the channels play crucial roles in facilitating the calcium influx necessary to trigger lymphocyte activation and proliferation. Using selective channel inhibitors in experimental animal models, in vivo studies further revealed the clinically relevant relationship between the channel expression and the development of chronic respiratory diseases, in which chronic inflammation or the overstimulation of cellular immunity in the airways is responsible for the pathogenesis. In chronic respiratory diseases, such as chronic obstructive pulmonary disease, asthma, diffuse panbronchiolitis and cystic fibrosis, in addition to the supportive management for the symptoms, the anti-inflammatory effects of macrolide antibiotics were shown to be effective against the over-activation or proliferation of T lymphocytes. Recently, we provided physiological and pharmacological evidence that macrolide antibiotics, together with calcium channel blockers, HMG-CoA reductase inhibitors, and nonsteroidal anti-inflammatory drugs, effectively suppress the Kv1.3-channel currents in lymphocytes, and thus exert anti-inflammatory or immunomodulatory effects. In this review article, based on the findings obtained from recent in vivo and in vitro studies, we address the novel therapeutic implications of targeting the lymphocyte Kv1.3-channels for the treatment of chronic or acute respiratory diseases.

Developments in the field of allergy in 2013 through the eyes of Clinical and Experimental Allergy

2013 was another exciting year for allergy in general and Clinical and Experimental Allergy in particular. In the field of asthma and rhinitis, there continued to be a focus on heterogeneity and phenotypes with increasing use of biostatistical techniques to determine clusters of similar populations. Obesity- and aspirin-associated disease are intriguing associations with asthma which were explored in a number of papers. We published a number of excellent papers on mechanisms of airway inflammation and how this relates to physiology, pathology, genetics and biomarkers in both human and experimental model systems. In terms of mechanisms, there is less on individual cell types in allergic disease at the moment, but the immunology of allergic disease continued to fascinate our authors. Another area that was popular both in the mechanisms and in the epidemiology sections was early life events and how these lead to allergic disease, with an increasing focus on the role of the microbiome and how this influences immune tolerance. In the clinical allergy section, oral immunotherapy for food allergy is clearly a major topic of interest at the moment as was in vitro testing to distinguish between sensitization and allergic disease. There was less on inhalant allergy this year, but a good representation from the drug allergy community including some interesting work on non-IgE-mediated mechanisms. In the allergen section, important new allergens continue to be discovered, but the major focus as in the last couple of years was on working out how component-resolved approaches can improve diagnosis and management of food and venom allergy.

Mast cell mediators: their differential release and the secretory pathways involved

Mast cells (MC) are widely distributed throughout the body and are common at mucosal surfaces, a major host-environment interface. MC are functionally and phenotypically heterogeneous depending on the microenvironment in which they mature. Although MC have been classically viewed as effector cells of IgE-mediated allergic diseases, they are also recognized as important in host defense, innate and acquired immunity, homeostatic responses, and immunoregulation. MC activation can induce release of pre-formed mediators such as histamine from their granules, as well as release of de novo synthesized lipid mediators, cytokines, and chemokines that play diverse roles, not only in allergic reactions but also in numerous physiological and pathophysiological responses. Indeed, MC release their mediators in a discriminating and chronological manner, depending upon the stimuli involved and their signaling cascades (e.g., IgE-mediated or Toll-like receptor-mediated). However, the precise mechanisms underlying differential mediator release in response to these stimuli are poorly known. This review summarizes our knowledge of MC mediators and will focus on what is known about the discriminatory release of these mediators dependent upon diverse stimuli, MC phenotypes, and species of origin, as well as on the intracellular synthesis, storage, and secretory processes involved.

Immunopharmacological modulation of mast cells

Mast cells produce a wide spectrum of mediators and they have been implicated in several physiopathological conditions (e.g. allergic reactions and certain tumors). Pharmacologic agents that modulate the release of mediators from mast cells has helped to elucidate the biochemical mechanisms by which immunological and non-immunological stimuli activate these cells. Furthermore, the study of surface receptors and signaling pathways associated with mast cell activation revealed novel pharmacologic targets. Thus, the development of pharmacologic agents based on this new wave of knowledge holds promise for the treatment of several mast cell-mediated disorders.