Dexamethasone and FK506 inhibit expression of distinct subsets of chemokines in human mast cells

HDAC6-MYCN-CXCL3 axis mediates allergic inflammation and is necessary for allergic inflammation-promoted cellular interactions

Histone deacetylase 6 (HDAC6) has been shown to play an important role in allergic inflammation. This study hypothesized that novel downstream targets of HDAC6 would mediate allergic inflammation. Experiments employing HDAC6 knock out C57BL/6 mice showed that HDAC6 mediated passive cutaneous anaphylaxis (PCA) and passive systemic anaphylaxis (PSA). Antigen stimulation increased expression of N-myc (MYCN) and CXCL3 in an HDAC6-dependent manner in the bone marrow-derived mast cells. MYCN and CXCL3 were necessary for both PCA and PSA. The role of early growth response 3 (EGR3) in the regulation of HDAC6 expression has been reported. ChIP assays showed EGR3 as a direct regulator of MYCN. miR-34a-5p was predicted to be a negative regulator of MYCN. Luciferase activity assays showed miR-34a-5p as a direct regulator of MYCN. miR-34a-5p mimic negatively regulated PCA and PSA. MYCN decreased miR-34a-5p expression in antigen-stimulated rat basophilic leukemia cells (RBL2H3). MYCN was shown to bind to the promoter sequence of CXCL3. In an IgE-independent manner, recombinant CXCL3 protein increased expression of HDAC6, MYCN, and β-hexosaminidase activity in RBL2H3 cells. Mouse recombinant CXCL3 protein enhanced the angiogenic potential of the culture medium of RBL2H3. CXCL3 was necessary for the enhanced angiogenic potential of the culture medium of antigen-stimulated RBL2H3. The culture medium of RBL2H3 was able to induce M2 macrophage polarization in a CXCL3-dependent manner. Recombinant CXCL3 protein also increased the expression of markers of M2 macrophage. Thus, the identification of the novel role of HDAC6-MYCN-CXCL3 axis can help better understand the pathogenesis of anaphylaxis.

Structures and Anti-Allergic Activities of Natural Products from Marine Organisms

In recent years, allergic diseases have occurred frequently, affecting more than 20% of the global population. The current first-line treatment of anti-allergic drugs mainly includes topical corticosteroids, as well as adjuvant treatment of antihistamine drugs, which have adverse side effects and drug resistance after long-term use. Therefore, it is essential to find alternative anti-allergic agents from natural products. High pressure, low temperature, and low/lack of light lead to highly functionalized and diverse functional natural products in the marine environment. This review summarizes the information on anti-allergic secondary metabolites with a variety of chemical structures such as polyphenols, alkaloids, terpenoids, steroids, and peptides, obtained mainly from fungi, bacteria, macroalgae, sponges, mollusks, and fish. Molecular docking simulation is applied by MOE to further reveal the potential mechanism for some representative marine anti-allergic natural products to target the H1 receptor. This review may not only provide insight into information about the structures and anti-allergic activities of natural products from marine organisms but also provides a valuable reference for marine natural products with immunomodulatory activities.

New perspectives on the origins and heterogeneity of mast cells

Mast cells are immune cells of the haematopoietic lineage that are now thought to have multifaceted functions during homeostasis and in various disease states. Furthermore, while mast cells have been known for a long time to contribute to allergic disease in adults, recent studies, mainly in mice, have highlighted their early origins during fetal development and potential for immune functions, including allergic responses, in early life. Our understanding of the imprinting of mast cells by particular tissues of residence and their potential for regulatory interactions with organ systems such as the peripheral immune, nervous and vascular systems is also rapidly evolving. Here, we discuss the origins of mast cells and their diverse and plastic phenotypes that are influenced by tissue residence. We explore how divergent phenotypes and functions might result from both their hard-wired 'nature' defined by their ontogeny and the 'nurture' they receive within specialized tissue microenvironments.

A new ex vivo skin model for mechanistic understanding of putative anti-inflammatory topical therapeutics

Several in vitro models have been designed as test systems for inflammatory skin conditions, commonly using cell-culture or reconstructed human epidermis approaches. However, these systems poorly recapitulate the physiology and, importantly, the metabolism and biochemical activity of skin in vivo, whereas ex vivo skin culture models can retain these features of the tissue. Our objective was to develop a human ex vivo skin culture model to explore the pathophysiology of inflammatory dermatoses and for preclinical testing of potential therapeutic treatments. Following exogenous stimulation, tissue integrity and ability to induce inflammatory gene expression was retained, and stimulant concentrations and duration was optimised to mimic published data from inflammatory clinical biopsies of dermatitis and psoriasis patients. The validity and utility of the model was demonstrated when challenged with 5 drugs including a corticosteroid and vitamin D3 analogue, where inflammatory biomarkers were regulated in a manner consistent with the drugs' reported in vivo mechanisms of action. This model retains important inflammatory gene signals observed in human inflammatory dermatoses for preclinical evaluation of novel therapeutics.

Mechanism of Action and Efficacy of Immunosupressors in Lupus Nephritis

Approximately 70% of the patients with systemic lupus erythematosus will have clinical evidence of kidney damage during their evolution. Patients with impaired renal function at onset and those with recurrent flares have a poor prognosis. Understanding the mechanism of action of immunosuppressants is essential for proper prescription. Steroids inhibit the DNA sequence that promotes the release of inflammatory cytokines. Phosphoramide mustard, metabolite of cyclophosphamide, cross-link with the DNA, causing the aggregation of an alkyl group, causing cell death. Mycophenolate inhibits inosine monophosphate dehydrogenase, prevents de novo synthesis of guanine, inducing cell arrest in S phase. Azathioprine blocks the synthesis of purines and induces apoptosis. Calcineurin inhibitors prevent the dephosphorylation of NFAT and reduce the production of interleukin 2. Antimalarials alter the enzymatic release of lysosomes by increasing intravesicular pH. The mechanism of action of rituximab is related to complement-dependent cytotoxicity and the elimination of anti-CD20-labeled B cells. Progress in the knowledge and management of low doses of steroids may change the current paradigm and reduce the frequency of related adverse events. Mycophenolate seems to be a better choice than cyclophosphamide for induction, it is also preferred over azathioprine as a maintenance immunosuppressive agent, although azathioprine is preferred in women with a desire for conception, those pregnant, or with low resources. For treatment-resistant cases, tacrolimus, rituximab or belimumab may be effective. Ongoing clinical trials with new drugs offer promising results.

Increased Thrombin-Activatable Fibrinolysis Inhibitor in Response to Sublingual Immunotherapy for Allergic Rhinitis

OBJECTIVES/HYPOTHESIS

The objective of this study was to determine the role of thrombin-activatable fibrinolysis inhibitor (TAFI) as a candidate biomarker for therapeutic efficacy of sublingual immunotherapy (SLIT) and to identify the role of TAFI in the pathogenesis of allergic rhinitis (AR).

STUDY DESIGN

Retrospective cohort study and laboratory study.

METHODS

Serum was collected from patients with allergies to Japanese cedar pollen before, during, and after treatment with SLIT. We measured the levels of immunoreactive TAFI, C3a, and C5a in serum by enzyme-linked immunosorbent assay (ELISA) and assessed their relative impact on a combined symptom-medication score. We also examined the impact of TAFI on mast cells and fibroblasts in experiments performed in vitro.

RESULTS

Serum levels of TAFI increased significantly in response to SLIT. By contrast, serum C3a levels decreased significantly over time; we observed a significant negative correlation between serum levels of TAFI versus C3a and symptom-medication score. Mast cell degranulation was inhibited in response to TAFI, as it was the expression of both CCL11 and CCL5 in cultured fibroblasts.

CONCLUSIONS

High serum levels of TAFI may be induced by SLIT. TAFI may play a critical protective role in pathogenesis of AR by inactivating C3a and by inhibiting mast cell degranulation and chemokines expression in fibroblasts.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

Sulforaphane has a therapeutic effect in an atopic dermatitis murine model and activates the Nrf2/HO‑1 axis

Atopic dermatitis (AD), a chronic inflammatory skin disease, is characterized by intense itching and recurrent eczematous lesions. Sulforaphane is known to attenuate oxidative stress, and tissue or cell damage in cerebral ischemia, brain inflammation and intracerebral hemorrhage. In the present study, a 2,4‑dinitrochlorobenzene (DNCB)‑induced AD mouse model was developed, and ear thickness, dermatitis score, eosinophil count, mast cell infiltration, and serum IgE levels were measured in DNCB‑induced AD and sulforaphane‑treated groups to demonstrate the therapeutic effects of sulforaphane. AD symptoms of DNCB‑induced mice were attenuated by sulforaphane treatment compared with those of negative control mice; furthermore, eosinophil count, mast cell infiltration and serum IgE levels were also reduced by sulforaphane treatment in DNCB‑induced AD mice. Western blot assays revealed that the expression levels of nuclear factor‑E2‑related factor 2 (Nrf2) and heme oxygenase-1 (HO‑1), which exhibit oxidation resistance, were increased by sulforaphane treatment in DNCB‑induced AD mice. The present study suggested that sulforaphane exerted a therapeutic effect in the AD mouse model through the activation of the Nrf2/HO‑1 axis as well as the suppression of Janus kinase 1/STAT3 signaling pathway.

Tangeretin promotes regulatory T cell differentiation by inhibiting Notch1/Jagged1 signaling in allergic rhinitis

BACKGROUND AND OBJECTIVE

Tangeretin demonstrates broad anti-inflammatory effects. The present study aimed to assess whether tangeretin functions in regulating T-regulatory cells (Tregs) and alleviating allergic rhinitis (AR).

METHODS

An ovalbumin (OVA)-induced AR animal model was constructed to monitor the changes in the allergic symptom score, OVA-specific IgE titers, histopathological characteristics and T-helper cell (Th1, Th2, and Th17)-related cytokine levels under tangeretin or dexamethasone (DXM) administration. The expression levels of Notch1/Jagged1 and FOXP3, and the proportion of Tregs in the spleens of these animals, were also detected. Furthermore, purified naive CD4 + T cells were utilized to assess the effects of tangeretin on Notch1 expression and their differentiation in vitro.

RESULTS

Both tangeretin and DXM administration alleviated airway inflammation, decreased the production of serum OVA-induced IgE, but only tangeretin administration restored the balance of cytokine profiles compared with those in the AR group. The abundance of splenic CD4 + CD25 + FOXP3 + Treg cells and the transcription factor FOXP3 were significantly increased under tangeretin treatment, either in AR mice or in naïve CD4 + T-cell differentiation, followed by a concomitant reduction in Notch1/Jagged1 expression. However, as a positive control, the treatment of allergic rhinitis with dexamethasone was not related to the expression of Notch1/Jagged1 or the differentiation of Treg cells.

CONCLUSION

Tangeretin could promote regulatory T cell responses by inhibiting Notch1/Jagged1 expression, followed by promoting FOXP3/Treg cell differentiation and thus could serve as a novel curative therapeutic for AR.

FK506 (tacrolimus) causes pain sensation through the activation of transient receptor potential ankyrin 1 (TRPA1) channels

FK506 (tacrolimus) is an immunosuppressant widely used as an ointment in the treatment of atopic dermatitis. However, local application of FK506 can evoke burning sensations in atopic dermatitis patients, and its mechanisms are unknown. In this study, we found that FK506 activates transient receptor potential ankyrin 1 (TRPA1) channels. In Ca2+-imaging experiments, increases in intracellular Ca2+ concentrations ([Ca2+]i) by FK506 were observed in HEK293T cells expressing hTRPA1 or hTRPM8. FK506-induced currents were observed in HEK293T cells expressing hTRPA1 or mTRPA1, but less or not at all in cells expressing hTRPV1 or hTRPM8 using a patch-clamp technique. FK506 also evoked single-channel opening of hTRPA1 in an inside-out configuration. FK506-induced [Ca2+]i increases were also observed in TRPA1-expressing mouse primary sensory neurons. Furthermore, injection of FK506 evoked licking or biting behaviors and these behaviors were almost abolished in TRPA1 knockout mice. These results indicate that FK506 might cause pain sensations through TRPA1 activation.

The controversial role of mast cells in fibrosis

Fibrosis is a medical condition characterized by an excessive deposition of extracellular matrix compounds such as collagen in tissues. Fibrotic lesions are present in many diseases and can affect all organs. The excessive extracellular matrix accumulation in these conditions can often have serious consequences and in many cases be life-threatening. A typical event seen in many fibrotic conditions is a profound accumulation of mast cells (MCs), suggesting that these cells can contribute to the pathology. Indeed, there is now substantialv evidence pointing to an important role of MCs in fibrotic disease. However, investigations from various clinical settings and different animal models have arrived at partly contradictory conclusions as to how MCs affect fibrosis, with many studies suggesting a detrimental role of MCs whereas others suggest that MCs can be protective. Here, we review the current knowledge of how MCs can affect fibrosis.

Tacrolimus ointment for the treatment of adult and pediatric atopic dermatitis: Review on safety and benefits

Atopic dermatitis (AD) requires long-term management, mainly with topical anti-inflammatory agents. Topical corticosteroids (TCS) and tacrolimus ointment (TAC-O) are recommended as first-line treatments for AD. However, the long-term use of TCS is limited by cutaneous adverse events such as skin atrophy. For TAC-O, Japanese and US labelings were updated in 2003 and 2006, respectively, to include a boxed warning about a theoretical risk of skin cancer and lymphoma in patients treated with topical calcineurin inhibitors. However, TAC-O has been used worldwide for longer than 15 years to treat adult and pediatric patients with AD. Available data suggest that TAC-O is effective and well tolerated, and can improve quality of life. TAC-O has successfully been used in the proactive management of AD consisting of long-term intermittent use to prevent, delay or reduce the occurrence of AD flares. Systemic drug absorption after TAC-O application is negligible and unlikely to result in systemic immunosuppression. There is currently no strong evidence of an increased rate of malignancy in treated patients, and observational data from postmarketing surveillance studies have shown no safety concerns. In the absence of robust evidence, the warning about the carcinogenic potential in the Japanese labeling for TAC-O does not appear justified and should be reconsidered. This mitigation of description would allow adult and pediatric patients with AD to receive the effective treatment more appropriately.

Mechanistic insights into topical tacrolimus for the treatment of atopic dermatitis

More than 15 years have passed since the clinical launch of topical tacrolimus for the treatment of atopic dermatitis. Its efficacy and safety have been clearly demonstrated in many global and domestic short-term and long-term clinical trials. Although the prolonged external application of steroids causes many adverse reactions including cutaneous atrophy, no such reactions occur with the use of topical tacrolimus. Therefore, the therapeutic guidelines recommend a combined topical treatment with tacrolimus and steroids. Tacrolimus is a potent immunosuppressant. However, recent studies have revealed its diverse action on the cardinal pathomechanisms of atopic dermatitis. In this review, we summarize the mechanistic role of tacrolimus in various aspects of allergic inflammation including mast cell activation, innate allergic response, pruritus, sensory nerve activation, and skin barrier dysfunction.

Pathogenesis of Recalcitrant Chronic Rhinosinusitis: The Emerging Role of Innate Immune Cells

Chronic rhinosinusitis (CRS) is a major part of the recalcitrant inflammatory diseases of the upper airway that needs enormous socioeconomic burden. T helper (Th) 2 type immune responses recruiting eosinophils were the most well-known immune players in CRS pathogenesis especially in western countries. By the piling up of a vast amount of researches to elucidate the pathogenic mechanism of CRS recently, heterogeneous inflammatory processes were found to be related to the phenotypes of CRS. Recently more cells other than T cells were in the focus of CRS pathogenesis, such as the epithelial cell, macrophage, innate lymphoid cells, and neutrophils. Here, we reviewed the recent research focusing on the innate immune cells related to CRS pathogenesis.

LAT is essential for the mast cell stabilising effect of tHGA in IgE-mediated mast cell activation

Mast cells play a central role in the pathogenesis of allergic reaction. Activation of mast cells by antigens is strictly dependent on the influx of extracellular calcium that involves a complex interaction between signalling molecules located within the cells. We have previously reported that tHGA, an active compound originally isolated from a local shrub known as Melicope ptelefolia, prevented IgE-mediated mast cell activation and passive systemic anaphylaxis by suppressing the release of interleukin-4 (IL-4) and tumour necrosis factor (TNF)-α from activated rat basophilic leukaemia (RBL)-2H3 cells. However, the mechanism of action (MOA) as well as the molecular target underlying the mast cell stabilising effect of tHGA has not been previously investigated. In this study, DNP-IgE-sensitised RBL-2H3 cells were pre-treated with tHGA before challenged with DNP-BSA. To dissect the MOA of tHGA in IgE-mediated mast cell activation, the effect of tHGA on the transcription of IL-4 and TNF-α mRNA was determined using Real Time-Polymerase Chain Reaction (qPCR) followed by Calcium Influx Assay to confirm the involvement of calcium in the activation of mast cells. The protein lysates were analysed by using Western Blot to determine the effect of tHGA on various important signalling molecules in the LAT-PLCγ-MAPK and PI3K-NFκB pathways. In order to identify the molecular target of tHGA in IgE-mediated mast cell activation, the LAT and LAT2 genes in RBL-2H3 cells were knocked-down by using RNA interference to establish a LAT/LAT2 competition model. The results showed that tHGA inhibited the transcription of IL-4 and TNF-α as a result of the suppression of calcium influx in activated RBL-2H3 cells. The results from Western Blot revealed that tHGA primarily inhibited the LAT-PLCγ-MAPK pathway with partial inhibition on the PI3K-p65 pathway without affecting Syk. The results from RNAi further demonstrated that tHGA failed to inhibit the release of mediators associated with mast cell degranulation under the LAT/LAT2 competition model in the absence of LAT. Collectively, this study concluded that the molecular target of tHGA could be LAT and may provide a basis for the development of a mast cell stabiliser which targets LAT.

Human eosinophils constitutively express a unique serine protease, PRSS33

BACKGROUND

Eosinophils play important roles in asthma, especially airway remodeling, by producing various granule proteins, chemical mediators, cytokines, chemokines and proteases. However, protease production by eosinophils is not fully understood. In the present study, we investigated the production of eosinophil-specific proteases/proteinases by transcriptome analysis.

METHODS

Human eosinophils and other cells were purified from peripheral blood by density gradient sedimentation and negative/positive selections using immunomagnetic beads. Protease/proteinase expression in eosinophils and release into the supernatant were evaluated by microarray analysis, qPCR, ELISA, flow cytometry and immunofluorescence staining before and after stimulation with eosinophil-activating cytokines and secretagogues. mRNAs for extracellular matrix proteins in human normal fibroblasts were measured by qPCR after exposure to recombinant protease serine 33 (PRSS33) protein (rPRSS33), created with a baculovirus system.

RESULTS

Human eosinophils expressed relatively high levels of mRNA for metalloproteinase 25 (MMP25), a disintegrin and metalloprotease 8 (ADAM8), ADAM10, ADAM19 and PRSS33. Expression of PRSS33 was the highest and eosinophil-specific. PRSS33 mRNA expression was not affected by eosinophil-activating cytokines. Immunofluorescence staining showed that PRSS33 was co-localized with an eosinophil granule protein. PRSS33 was not detected in the culture supernatant of eosinophils even after stimulation with secretagogues, but its cell surface expression was increased. rPRSS33 stimulation of human fibroblasts increased expression of collagen and fibronectin mRNAs, at least in part via protease-activated receptor-2 activation.

CONCLUSIONS

Activated eosinophils may induce fibroblast extracellular matrix protein synthesis via cell surface expression of PRSS33, which would at least partly explain eosinophils' role(s) in airway remodeling.

Neutrophils are a major source of the epithelial barrier disrupting cytokine oncostatin M in patients with mucosal airways disease

BACKGROUND

We have previously shown that oncostatin M (OSM) levels are increased in nasal polyps (NPs) of patients with chronic rhinosinusitis (CRS), as well as in bronchoalveolar lavage fluid, after segmental allergen challenge in allergic asthmatic patients. We also showed in vitro that physiologic levels of OSM impair barrier function in differentiated airway epithelium.

OBJECTIVE

We sought to determine which hematopoietic or resident cell type or types were the source of the OSM expressed in patients with mucosal airways disease.

METHODS

Paraffin-embedded NP sections were stained with fluorescence-labeled specific antibodies against OSM, GM-CSF, and hematopoietic cell-specific markers. Live cells were isolated from NPs and matched blood samples for flow cytometric analysis. Neutrophils were isolated from whole blood and cultured with the known OSM inducers GM-CSF and follistatin-like 1, and OSM levels were measured in the supernatants. Bronchial biopsy sections from control subjects, patients with moderate asthma, and patients with severe asthma were stained for OSM and neutrophil elastase.

RESULTS

OSM staining was observed in NPs, showed colocalization with neutrophil elastase (n = 10), and did not colocalize with markers for eosinophils, macrophages, T cells, or B cells (n = 3-5). Flow cytometric analysis of NPs (n = 9) showed that 5.1% ± 2% of CD45+ cells were OSM+, and of the OSM+ cells, 56% ± 7% were CD16+Siglec-8-, indicating neutrophil lineage. Only 0.6 ± 0.4% of CD45+ events from matched blood samples (n = 5) were OSM+, suggesting that increased OSM levels in patients with CRS was locally stimulated and produced. A majority of OSM+ neutrophils expressed arginase 1 (72.5% ± 12%), suggesting an N2 phenotype. GM-CSF levels were increased in NPs compared with those in control tissue and were sufficient to induce OSM production (P < .001) in peripheral blood neutrophils in vitro. OSM+ neutrophils were also observed at increased levels in biopsy specimens from patients with severe asthma. Additionally, OSM protein levels were increased in induced sputum from asthmatic patients compared with that from control subjects (P < .05).

CONCLUSIONS

Neutrophils are a major source of OSM-producing cells in patients with CRS and severe asthma.

Mast cells in asthma--state of the art

Mast cells (MCs) play a central role in tissue homoeostasis, sensing the local environment through numerous innate cell surface receptors. This enables them to respond rapidly to perceived tissue insults with a view to initiating a co-ordinated programme of inflammation and repair. However, when the tissue insult is chronic, the ongoing release of multiple pro-inflammatory mediators, proteases, cytokines and chemokines leads to tissue damage and remodelling. In asthma, there is strong evidence of ongoing MC activation, and their mediators and cell-cell signals are capable of regulating many facets of asthma pathophysiology. This article reviews the evidence behind this.

Proteome analysis of mast cell releasates reveals a role for chymase in the regulation of coagulation factor XIIIA levels via proteolytic degradation

BACKGROUND

Mast cells are significantly involved in IgE-mediated allergic reactions; however, their roles in health and disease are incompletely understood.

OBJECTIVE

We aimed to define the proteome contained in mast cell releasates on activation to better understand the factors secreted by mast cells that are relevant to the contribution of mast cells in diseases.

METHODS

Bone marrow-derived cultured mast cells (BMCMCs) and peritoneal cell-derived mast cells were used as "surrogates" for mucosal and connective tissue mast cells, respectively, and their releasate proteomes were analyzed by mass spectrometry.

RESULTS

Our studies showed that BMCMCs and peritoneal cell-derived mast cells produced substantially different releasates following IgE-mediated activation. Moreover, we observed that the transglutaminase coagulation factor XIIIA (FXIIIA) was one of the most abundant proteins contained in the BMCMC releasates. Mast cell-deficient mice exhibited increased FXIIIA plasma and activity levels as well as reduced bleeding times, indicating that mast cells are more efficient in their ability to downregulate FXIIIA than in contributing to its amounts and functions in homeostatic conditions. We found that human chymase and mouse mast cell protease-4 (the mouse homologue of human chymase) had the ability to reduce FXIIIA levels and function via proteolytic degradation. Moreover, we found that chymase deficiency led to increased FXIIIA amounts and activity, as well as reduced bleeding times in homeostatic conditions and during sepsis.

CONCLUSIONS

Our study indicates that the mast cell protease content can shape its releasate proteome. Moreover, we found that chymase plays an important role in the regulation of FXIIIA via proteolytic degradation.

Repeated FcεRI triggering reveals modified mast cell function related to chronic allergic responses in tissue

BACKGROUND

Activation of mast cells through FcεRI plays an important role in acute allergic reactions. However, little is known about the function of mast cells in patients with chronic allergic inflammation or the effect of repeated FcεRI triggering occurring in such responses.

OBJECTIVE

We aimed to identify changes in mast cell function after repeated FcεRI triggering and to correlate these changes to chronic allergic responses in tissue.

METHODS

Human cord blood-derived mast cells were treated for 2 weeks with anti-IgE. The function of naive or treated mast cells was analyzed by means of RNA sequencing, quantitative RT-PCR, flow cytometry, and functional assays. Protein secretion was measured with ELISAs and multiplex assays.

RESULTS

We observed several changes in mast cell function after repeated anti-IgE triggering. Although the acute response was dampened, we identified 289 genes significantly upregulated after repeated anti-IgE. Most of these genes (84%) were not upregulated after a single anti-IgE stimulus, indicating a significantly different response mode characterized by increased antigen presentation, response to bacteria, and chemotaxis. Changes in mast cell function were related to changes in expression of the transcription factors RXRA and BATF and others. Importantly, we found a substantial overlap between genes upregulated after repeated anti-IgE triggering and genes upregulated in tissue from patients with chronic allergy, in particular those of patients with chronic rhinosinusitis.

CONCLUSION

Our study provides evidence for intrinsic modulation of mast cell function on repeated FcεRI-mediated activation. The overlap with gene expression in tissues is suggestive of a direct link between repeated IgE-mediated activation of mast cells and chronic allergy.

Immunopathology of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a heterogeneous disease characterized by local inflammation of the upper airways and sinuses which persists for at least 12 weeks. CRS can be divided into two phenotypes dependent on the presence of nasal polyps (NPs); CRS with NPs (CRSwNP) and CRS without NPs (CRSsNP). Immunological patterns in the two diseases are known to be different. Inflammation in CRSsNP is rarely investigated and limited studies show that CRSsNP is characterized by type 1 inflammation. Inflammation in CRSwNP is well investigated and CRSwNP in Western countries shows type 2 inflammation and eosinophilia in NPs. In contrast, mixed inflammatory patterns are found in CRSwNP in Asia and the ratio of eosinophilic NPs and non-eosinophilic NPs is almost 50:50 in these countries. Inflammation in eosinophilic NPs is mainly controlled by type 2 cytokines, IL-5 and IL-13, which can be produced from several immune cells including Th2 cells, mast cells and group 2 innate lymphoid cells (ILC2s) that are all elevated in eosinophilic NPs. IL-5 strongly induces eosinophilia. IL-13 activates macrophages, B cells and epithelial cells to induce recruitment of eosinophils and Th2 cells, IgE mediated reactions and remodeling. Epithelial derived cytokines, TSLP, IL-33 and IL-1 can directly and indirectly control type 2 cytokine production from these cells in eosinophilic NPs. Recent clinical trials showed the beneficial effect on eosinophilic NPs and/or asthma by monoclonal antibodies against IL-5, IL-4Rα, IgE and TSLP suggesting that they can be therapeutic targets for eosinophilic CRSwNP.

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.

Stimulus-selective regulation of human mast cell gene expression, degranulation and leukotriene production by fluticasone and salmeterol

Despite the fact that glucocorticoids and long acting beta agonists are effective treatments for asthma, their effects on human mast cells (MC) appear to be modest. Although MC are one of the major effector cells in the underlying inflammatory reactions associated with asthma, their regulation by these drugs is not yet fully understood and, in some cases, controversial. Using a human immortalized MC line (LAD2), we studied the effects of fluticasone propionate (FP) and salmeterol (SM), on the release of early and late phase mediators. LAD2 cells were pretreated with FP (100 nM), SM (1 µM), alone and in combination, at various incubation times and subsequently stimulated with agonists substance P, C3a and IgE/anti-IgE. Degranulation was measured by the release of β-hexosaminidase. Cytokine and chemokine expression were measured using quantitative PCR, ELISA and cytometric bead array (CBA) assays. The combination of FP and SM synergistically inhibited degranulation of MC stimulated with substance P (33% inhibition compared to control, n = 3, P<.05). Degranulation was inhibited by FP alone, but not SM, when MC were stimulated with C3a (48% inhibition, n = 3, P<.05). As previously reported, FP and SM did not inhibit degranulation when MC were stimulated with IgE/anti-IgE. FP and SM in combination inhibited substance P-induced release of tumor necrosis factor (TNF), CCL2, and CXCL8 (98%, 99% and 92% inhibition, respectively, n = 4, P<.05). Fluticasone and salmeterol synergistically inhibited mediator production by human MC stimulated with the neuropeptide substance P. This synergistic effect on mast cell signaling may be relevant to the therapeutic benefit of combination therapy in asthma.

Mast cells as targets for immunotherapy of solid tumors

Mast cells have historically been studied mainly in the context of allergic disease. In recent years, we have come to understand the critical importance of mast cells in tissue remodeling events and their role as sentinel cells in the induction and development of effective immune responses to infection. Studies of the role of mast cells in tumor immunity are more limited. The pro-tumorigenic role of mast cells has been widely reported. However, mast cell infiltration predicts improved prognosis in some cancers, suggesting that their prognostic value may be dependent on other variables. Such factors may include the nature of local mast cell subsets and the various activation stimuli present within the tumor microenvironment. Experimental models have highlighted the importance of mast cells in orchestrating the anti-tumor events that follow immunotherapies that target innate immunity. Mast cells are long-lived tissue resident cells that are abundant around many solid tumors and are radiation resistant making them unique candidates for combined treatment modalities. This review will examine some of the key roles of mast cells in tumor immunity, with a focus on potential immunotherapeutic interventions that harness the sentinel role of mast cells.

Thymic stromal lymphopoietin activity is increased in nasal polyps of patients with chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is associated with TH2-dominant inflammation. Thymic stromal lymphopoietin (TSLP) is a cytokine that triggers dendritic cell-mediated TH2 inflammatory responses and that enhances IL-1-dependent TH2 cytokine production in mast cells. Although increased TSLP mRNA levels have been found in nasal polyps (NPs), expression of TSLP protein and its function in patients with chronic rhinosinusitis (CRS) have not been fully explored.

OBJECTIVES

The objective of this study was to investigate the role of TSLP in patients with CRS.

METHODS

We investigated the presence and stability of TSLP protein in NPs using ELISA and Western blotting and investigated the function of TSLP in nasal tissue extracts with a bioassay based on activation of human mast cells.

RESULTS

Although TSLP mRNA levels were significantly increased in NP tissue from patients with CRSwNP compared with uncinate tissue from patients with CRS or control subjects, TSLP protein was significantly decreased in NP tissue, as detected by using the commercial ELISA kit. We found that recombinant TSLP was time-dependently degraded by NP extracts, and this degradation was completely inhibited by a protease inhibitor cocktail, suggesting that TSLP is sensitive to tissue proteases. Interestingly, NP extract-treated TSLP had higher activity in mast cells, although the amount of full-length TSLP was reduced up to 85%. NP extracts significantly enhanced IL-1β-dependent IL-5 production in mast cells compared with uncinate tissue homogenates, and responses were significantly inhibited by anti-TSLP, suggesting that NPs contain biologically relevant levels of TSLP activity.

CONCLUSION

TSLP and its metabolic products might play an important role in the inflammation seen in patients with CRSwNP.

Increased expression of factor XIII-A in patients with chronic rhinosinusitis with nasal polyps

BACKGROUND

Profound edema or formation of a pseudocyst containing plasma proteins is a prominent characteristic of nasal polyps (NP). However, the mechanisms underlying NP retention of plasma proteins in the submucosa remain unclear. Recently, we reported that impairment of fibrinolysis causes excessive fibrin deposition in NP and this might be involved in the retention of plasma proteins. Although the coagulation cascade plays a critical role in fibrin clot formation at extravascular sites, the expression and role of coagulation factors in NP remain unclear.

OBJECTIVE

The objective of this study was to investigate the expression of coagulation factors in patients with chronic rhinosinusitis (CRS).

METHODS

Sinonasal tissues were collected from patients with CRS and control subjects. We assayed mRNA for factor XIII-A (FXIII-A) by using real-time PCR and measured FXIII-A protein by means of ELISA, immunohistochemistry, and immunofluorescence.

RESULTS

FXIII-A mRNA levels were significantly increased in NP tissue from patients with CRS with NP (P < .001) compared with uncinate tissue from patients with CRS or control subjects. Similarly, FXIII-A protein levels were increased in NP. Immunofluorescence analysis revealed that FXIII-A expression in inflammatory cells and FXIII-A(+) cell numbers were significantly increased in NP. Most FXIII-A staining was observed within CD68(+)/CD163(+) M2 macrophages in NP. Levels of FXIII-A correlated with markers of M2 macrophages, suggesting that M2 macrophages are major FXIIIA-producing cells in NP.

CONCLUSION

Overproduction of FXIII-A by M2 macrophages might contribute to the excessive fibrin deposition in the submucosa of NP, which might contribute to the tissue remodeling and pathogenesis of CRS with NP.

Acteoside inhibits type Ι allergy through the down-regulation of Ca/NFAT and JNK MAPK signaling pathways in basophilic cells

We have previously reported that acteoside inhibits the release of β-hexosaminidase from immunoglobulin E (IgE)-sensitized and bovine serum albumin-stimulated rat basophilic leukemia cells as well as the intracellular calcium level, release of histamine from, and production of tumor necrosis factor-alpha and interleukin-4 in human basophilic (KU812) cells. However, the molecular mechanism underlying the anti-allergic effects of acteoside has not yet been elucidated. Here, we used microarray analysis to determine the global gene expression profile of KU812 cells treated with acteoside and calcium ionophore A23187 plus phorbol-12-myristate 13-acetate (A23187+PMA), and the results were validated by real-time polymerase chain reaction (PCR) and Western blotting. Microarray analysis results showed that of the 201 genes in the microarray, 149 genes were up-regulated, while 52 genes were down-regulated. The significantly down-regulated genes have functions as chemokine and IgE receptors, as well as for immune response. Results of the validation of the microarray results using real-time PCR showed a significant decrease in the expressions of Fc fragment of IgE, high affinity I, receptor for; alpha polypeptide (FCER1A) and nuclear factor of activated T cell, cytoplasmic, calcineurin-dependent 1 (NFATC1) genes. Furthermore, Western blotting showed a decrease in the phosphorylation of mitogen-activated protein kinase (MAPK) Jun N terminal kinase (JNK), revealing the role of JNK MAPK in acteoside-mediated allergy inhibition. We determined that the anti-allergy effects of acteoside were due to the down-regulation of the expressions of the chemokine ligand 1 (CCL1), CCL2, CCL3, CCL4, FCER1A and NFATC1 genes and the inhibition of the MAPK pathway through decreased JNK phosphorylation.

Chronic rhinosinusitis with nasal polyps is characterized by B-cell inflammation and EBV-induced protein 2 expression

BACKGROUND

Despite the high prevalence and morbidity of chronic rhinosinusitis (CRS), little is known about the mechanisms that underlie its pathogenesis. Recent studies have suggested that B cells might play an important role in CRS.

OBJECTIVE

We sought to thoroughly characterize B lineage cells within sinus tissues of patients with CRS and healthy control subjects and to determine whether levels of EBV-induced protein 2, which is known to play an important role in the development of B-cell responses, were increased in patients with CRS.

METHODS

Cells isolated from sinus tissues of patients with CRS and healthy control subjects were characterized by means of flow cytometry and immunohistochemistry. Local production of antibodies was measured in tissue extracts, nasal lavage fluid, and sera by using multiplex bead arrays and ELISA. Quantitative RT-PCR, ELISA, and Western blotting were used to assess gene and protein expression from tissue extracts.

RESULTS

Nasal polyps (NPs) from patients with CRS had increased levels of both B cells and plasma cells compared with uncinate tissue from healthy control subjects (P<.05). NPs also contained significantly increased levels of several antibody isotypes compared with normal uncinate tissue (P<.05), but no differences in circulating antibody levels were found. Interestingly, levels of EBV-induced protein 2 were also increased in NPs (P<.05) and were positively correlated with expression of plasma cell markers (CD138 and B lymphocyte-induced maturation protein) in sinus tissue.

CONCLUSION

B cells and plasma cells are enriched in NPs, actively produce antibodies locally, and might contribute to chronic inflammation in patients with CRS. Elucidating the mechanisms that underlie this excessive local B-cell response might provide novel insights for the development of improved therapeutic strategies.

The chymase mouse mast cell protease 4 degrades TNF, limits inflammation, and promotes survival in a model of sepsis

Mouse mast cell protease 4 (mMCP-4), the mouse counterpart of human mast cell chymase, is thought to have proinflammatory effects in innate or adaptive immune responses associated with mast cell activation. However, human chymase can degrade the proinflammatory cytokine TNF, a mediator that can be produced by mast cells and many other cell types. We found that mMCP-4 can reduce levels of mouse mast cell-derived TNF in vitro through degradation of transmembrane and soluble TNF. We assessed the effects of interactions between mMCP-4 and TNF in vivo by analyzing the features of a classic model of polymicrobial sepsis, cecal ligation and puncture (CLP), in C57BL/6J-mMCP-4-deficient mice versus C57BL/6J wild-type mice, and in C57BL/6J-Kit(W-sh/W-sh) mice containing adoptively transferred mast cells that were either wild type or lacked mMCP-4, TNF, or both mediators. The mMCP-4-deficient mice exhibited increased levels of intraperitoneal TNF, higher numbers of peritoneal neutrophils, and increased acute kidney injury after CLP, and also had significantly higher mortality after this procedure. Our findings support the conclusion that mMCP-4 can enhance survival after CLP at least in part by limiting detrimental effects of TNF, and suggest that mast cell chymase may represent an important negative regulator of TNF in vivo.

Regulation of the CCL2 gene in pancreatic β-cells by IL-1β and glucocorticoids: role of MKP-1

Release of pro-inflammatory cytokines from both resident and invading leukocytes within the pancreatic islets impacts the development of Type 1 diabetes mellitus. Synthesis and secretion of the chemokine CCL2 from pancreatic β-cells in response to pro-inflammatory signaling pathways influences immune cell recruitment into the pancreatic islets. Therefore, we investigated the positive and negative regulatory components controlling expression of the CCL2 gene using isolated rat islets and INS-1-derived β-cell lines. We discovered that activation of the CCL2 gene by IL-1β required the p65 subunit of NF-κB and was dependent on genomic response elements located in the -3.6 kb region of the proximal gene promoter. CCL2 gene transcription in response to IL-1β was blocked by pharmacological inhibition of the IKKβ and p38 MAPK pathways. The IL-1β-mediated increase in CCL2 secretion was also impaired by p38 MAPK inhibition and by glucocorticoids. Moreover, multiple synthetic glucocorticoids inhibited the IL-1β-stimulated induction of the CCL2 gene. Induction of the MAP Kinase Phosphatase-1 (MKP-1) gene by glucocorticoids or by adenoviral-mediated overexpression decreased p38 MAPK phosphorylation, which diminished CCL2 gene expression, promoter activity, and release of CCL2 protein. We conclude that glucocorticoid-mediated repression of IL-1β-induced CCL2 gene transcription and protein secretion occurs in part through the upregulation of the MKP-1 gene and subsequent deactivation of the p38 MAPK. Furthermore, the anti-inflammatory actions observed with MKP-1 overexpression were obtained without suppressing glucose-stimulated insulin secretion. Thus, MKP-1 is a possible target for anti-inflammatory therapeutic intervention with preservation of β-cell function.

The effect of topical FK506 (tacrolimus) in a mouse model of allergic rhinitis

BACKGROUND

The management of allergic rhinitis (AR) encompasses education, pharmacotherapy, immunotherapy, and surgery. FK506 (tacrolimus) is an immunosuppressant that inhibits allergic reactions. The purpose of this study was to reveal whether FK506 treatment reduces allergic inflammation in an AR mouse model and to elucidate the mechanisms.

METHODS

Forty mice were divided into four groups: control, AR, FK (FK506), and dexamethasone (DEX). All mice except for the control group were sensitized by an i.p. injection of ovalbumin (OVA). After sensitization, the FK and DEX groups were treated with FK506 and DEX intranasally. All sensitized mice were challenged intranasally with OVA. Allergic symptoms and tissue eosinophil counts were recorded. Interleukin (IL)-5, interferon gamma, and IL-10 levels in nasal lavage fluid (NALF) and serum OVA-specific IgE levels were measured. T-bet, GATA-3, and Foxp3 mRNA expression in splenic mononuclear cells were determined by real-time polymerase chain reaction.

RESULTS

In the FK group and DEX group, allergic symptoms, serum OVA-specific IgE, tissue eosinophil counts, IL-5 in NALF, and GATA-3 mRNAs expression decreased (p < 0.05), and IL-10 in NALF and Foxp3 mRNAs expression increased compared with the AR group (p < 0.05). No significant difference was observed between the FK group and the DEX group.

CONCLUSION

These results suggest that topical FK506 may reduce allergic inflammation and have potency equal to DEX in the AR model. This mechanism may involve not only Th2 cells but also regulatory T cells. Additional studies are needed on FK506, but in the future, we can consider FK506 as an alternative to topical steroids in the treatment of AR.

Chu H, Peters AT, Tan BK, Conley DB, Grammer LC, Kern RC, Schleimer RP. Reduced expression of antimicrobial PLUNC proteins in nasal polyp tissues of patients with chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) is a disease characterized by inflammation of the nasal mucosa and paranasal sinuses. This inflammation may result in part from decreased epithelial barrier and innate immune responses, leading to frequent bacterial and fungal colonization. The objectives of this study were to investigate the expression of innate immune proteins of the palate lung and nasal epithelium clone (PLUNC) family in patients with CRS.

METHODS

Nasal tissue samples were collected from control subjects and CRS patients with and without nasal polyps. Expression of the members of the PLUNC family was analyzed by real-time PCR. Expression of SPLUNC1 and LPLUNC2 proteins was analyzed by ELISA, immunoblot, and immunohistochemical analysis.

RESULTS

Levels of mRNA for most of the members of the PLUNC family were profoundly reduced in nasal polyps (NPs) compared to uncinate tissue from control subjects or patients with CRS. LPLUNC2 and SPLUNC1 proteins were decreased in NPs of patients with CRS compared to uncinate tissue from control subjects. Immunohistochemical data revealed that within submucosal glands of sinonasal tissues, SPLUNC1 and LPLUNC2 were differentially expressed, in serous and mucous cells, respectively. The decrease in the expression of these molecules is probably explained by a decrease in the number of glands in NPs as revealed by correlations with levels of the glandular marker lactoferrin.

CONCLUSIONS

Decreased SPLUNC1 and LPLUNC2 in NPs reflect a profound decrease in the number of submucosal glands. Decreased glands may lead to a localized defect in the production and release of glandular innate defense molecules.

Airway epithelial cells activate TH2 cytokine production in mast cells through IL-1 and thymic stromal lymphopoietin

BACKGROUND

Airway epithelial cells are important regulators of innate and adaptive immunity. Although mast cells are known to play a central role in manifestations of allergic inflammation and are found in the epithelium in patients with T(H)2-related diseases, their role is incompletely understood.

OBJECTIVES

The objective of this study was to investigate the role of airway epithelial cells in the production of T(H)2 cytokines in mast cells.

METHODS

Normal human bronchial epithelial (NHBE) cells were stimulated with TNF, IL-4, IFN-γ, IL-17A, and double-stranded RNA (dsRNA) alone or in combination. Human mast cells were stimulated with epithelial cell-derived supernatants or cocultured with NHBE cells. T(H)2 cytokine responses were blocked with neutralizing antibodies.

RESULTS

Supernatants from IL-4- and dsRNA-stimulated NHBE cells significantly enhanced T(H)2 cytokine production from mast cells. The combination of IL-4 and dsRNA itself or supernatants from NHBE cells stimulated with other cytokines did not activate mast cells, suggesting that mast cell responses were induced by epithelial cell factors that were only induced by IL-4 and dsRNA. Epithelial supernatant-dependent T(H)2 cytokine production in mast cells was suppressed by anti-IL-1 and anti- thymic stromal lymphopoietin (TSLP) and was enhanced by anti-IL-1 receptor antagonist. Similar results were observed in coculture experiments. Finally, we found dsRNA-dependent production of IL-1, TSLP, and IL-1 receptor antagonist in NHBE cells was regulated by T(H) cytokines, and their ratio in NHBE cells correlated with T(H)2 cytokine production in mast cells.

CONCLUSIONS

Pathogens producing dsRNA, such as respiratory viral infections, might amplify local T(H)2 inflammation in asthmatic patients through the production of TSLP and IL-1 by epithelial cells and subsequent activation of T(H)2 cytokine production by mast cells in the airways.

IgE and mast cells in allergic disease

Immunoglobulin E (IgE) antibodies and mast cells have been so convincingly linked to the pathophysiology of anaphylaxis and other acute allergic reactions that it can be difficult to think of them in other contexts. However, a large body of evidence now suggests that both IgE and mast cells are also key drivers of the long-term pathophysiological changes and tissue remodeling associated with chronic allergic inflammation in asthma and other settings. Such potential roles include IgE-dependent regulation of mast-cell functions, actions of IgE that are largely independent of mast cells and roles of mast cells that do not directly involve IgE. In this review, we discuss findings supporting the conclusion that IgE and mast cells can have both interdependent and independent roles in the complex immune responses that manifest clinically as asthma and other allergic disorders.

IgE, mast cells, and eosinophils in atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with specific immune and inflammatory mechanisms. Atopy is among the major features of the diagnosis criteria for AD but is not an essential feature. Thus, patients diagnosed with AD can be atopic or non-atopic. This review focuses on the role of IgE, mast cells, and eosinophils in the pathogenesis of AD. The known functions of IgE in allergic inflammation suggest that IgE and IgE-mediated mast cell and eosinophil activation contribute to AD, but direct evidence supporting this is scarce. The level of IgE (thus the degree of allergic sensitization) is associated with severity of AD and contributed by abnormality of skin barrier, a key feature of AD. The function of IgE in development of AD is supported by the beneficial effect of anti-IgE therapy in a number of clinical studies. The role of mast cells in AD is suggested by the increase in the mast cell number and mast cell activation in AD lesions and the association between mast cell activation and AD. It is further suggested by their role in mouse models of AD as well as by the effect of therapeutic agents for AD that can affect mast cells. The role of eosinophils in AD is suggested by the presence of eosinophilia in AD patients and eosinophil infiltrates in AD lesions. It is further supported by information that links AD to cytokines and chemokines associated with production, recruitment, and activation of eosinophils.

Human intestinal mast cells are a potent source of multiple chemokines

Mast cells are key effector cells of immediate type allergic reactions. Upon activation they release a broad array of pre-stored and de novo synthesized mediators including immunoregulatory cytokines and chemokines. Here, we analyzed the chemokine profile expressed by mature human mast cells. Human mast cells were isolated from intestinal tissue and cultured with stem cell factor (SCF) in the presence or absence of IL-4 for 10d. Cells were stimulated by cross-linking of the high affinity IgE receptor (FcεRI) and/or by SCF. Chemokine and chemokine receptor mRNA expression was determined by real-time RT-PCR and chemokine release was measured by multiplex bead immunoassay. Out of 43 chemokines and 19 chemokine receptors human intestinal mast cells express 27 chemokines and nine chemokine receptors. Twelve chemokines (CCL1, CCL2, CCL3, CCL4, CCL5, CCL7, CCL18, CCL20, CXCL2, CXCL3, CXCL8, and XCL1) were more than four-fold up-regulated in response to FcεRI cross-linking. Combination of pre-culture with IL-4 and/or stimulation with SCF in addition to FcεRI cross-linking further increased the antigen-dependent expression of mRNA for most chemokines. In contrast, the expression of CCL20, CXCL2, and CXCL3 was strongly inhibited by IL-4 treatment. In conclusion, human intestinal mast cells express a broad spectrum of different chemokines underlining their important role as immunoregulatory cells. Furthermore, combined treatment with IL-4 and SCF increases the antigen-mediated expression and release of multiple chemokines, but IL-4 priming inhibits the expression of CCL20, CXCL2, and CXCL3.

Imiquimod clears tumors in mice independent of adaptive immunity by converting pDCs into tumor-killing effector cells

Imiquimod is a synthetic compound with antitumor properties; a 5% cream formulation is successfully used to treat skin tumors. The antitumor effect of imiquimod is multifactorial, although its ability to modulate immune responses by triggering TLR7/8 is thought to be key. Among the immune cells suggested to be involved are plasmacytoid DCs (pDCs). However, a direct contribution of pDCs to tumor killing in vivo and the mechanism of their recruitment to imiquimod-treated sites have never been demonstrated. Using a mouse model of melanoma, we have now demonstrated that pDCs can directly clear tumors without the need for the adaptive immune system. Topical imiquimod treatment led to TLR7-dependent and IFN-α/β receptor 1-dependent (IFNAR1-dependent) upregulation of expression of the chemokine CCL2 in mast cells. This was essential to induce skin inflammation and for the recruitment of pDCs to the skin. The recruited pDCs were CD8α+ and induced tumor regression in a TLR7/MyD88- and IFNAR1-dependent manner. Lack of TLR7 and IFNAR1 or depletion of pDCs or CD8α+ cells from tumor-bearing mice completely abolished the effect of imiquimod. TLR7 was essential for imiquimod-stimulated pDCs to produce IFN-α/β, which led to TRAIL and granzyme B secretion by pDCs via IFNAR1 signaling. Blocking these cytolytic molecules impaired pDC-mediated tumor killing. Our results demonstrate that imiquimod treatment leads to CCL2-dependent recruitment of pDCs and their transformation into a subset of killer DCs able to directly eliminate tumor cells.

Increased expression of CC chemokine ligand 18 in patients with chronic rhinosinusitis with nasal polyps

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is associated with T(H)2-dominant inflammation, including eosinophilia, which is in contrast to chronic rhinosinusitis (CRS) without nasal polyps (NPs). CC chemokine ligand 18 (CCL18)/pulmonary and activation-regulated chemokine is known to recruit naive T cells, B cells, and immature dendritic cells, as well as to activate fibroblasts. CCL18 is thought to be involved in T(H)2-related inflammatory diseases, including asthma and atopic dermatitis.

OBJECTIVE

The objective of this study was to investigate the expression of CCL18 in patients with CRS.

METHODS

Using NP tissue and uncinate tissue (UT) from control subjects and patients with CRS, we examined the expression of CCL18 mRNA using real-time PCR and measured CCL18 protein using ELISA, Western blotting, and immunofluorescence.

RESULTS

Compared with UT tissue from control subjects, CCL18 mRNA levels were significantly increased in NPs (P < .001) and UT (P < .05) from patients with CRSwNP but not in UT from patients with CRS without NPs. Similarly, CCL18 protein levels were increased in NPs and UT from patients with CRSwNP, and levels were even higher in patients with Samter's triad. Immunohistochemical analysis revealed CCL18 expression in inflammatory cells, and CCL18(+) cell numbers were significantly increased in NPs. Immunofluorescence data showed colocalization of CCL18 in CD68(+)/CD163(+)/macrophage mannose receptor-positive M2 macrophages and tryptase-positive mast cells in NPs. Levels of CCL18 correlated with markers of M2 macrophages but not with tryptase levels, suggesting that M2 macrophages are major CCL18-producing cells in NPs.

CONCLUSION

Overproduction of CCL18 might contribute to the pathogenesis of CRSwNP through its known activities, which include recruitment of lymphocytes and dendritic cells, activation of fibroblasts, and initiation of local inflammation.

Analysis of chemokine and chemokine receptor expression in squamous cell carcinoma of the head and neck (SCCHN) cell lines

The purpose of this work was to analyze chemokine and chemokine receptor expression in untreated and in irradiated squamous cell carcinoma of the head and neck (SCCHN) tumor cell lines, aiming at the establishment of assays to test for the relevance of chemokine and chemokine receptor expression in the response of SCCHN to radiotherapy and radiochemotherapy. Five low passage and 10 established SCCHN lines, as well as two normal cell lines, were irradiated at 2 Gy or sham-irradiated, and harvested between 1 and 48 h after treatment. For chemokines with CC and CXC structural motifs and their receptors, transcript levels of target and reference genes were quantified relatively by real-time PCR. In addition, CXCL1 and CXCL12 protein expression was analyzed by ELISA. A substantial variation in chemokine and chemokine receptor expression between SCCHN was detected. Practically, all cell lines expressed CCL5 and CCL20, while CCL2 was expressed in normal cells and in some of the tumor cell lines. CXCL1, CXCL2, CXCL3, CXCL10, and CXCL11 were expressed in the vast majority of the cell lines, while the expression of CXCL9 and CXCL12 was restricted to fibroblasts and few tumor cell lines. None of the analyzed cell lines expressed the chemokines CCL3, CCL4, or CCL19. Of the receptors, transcript expression of CCR1, CCR2, CCR3, CCR5, CCR7, CCXR2, and CCXR3 was not detected, and CCR6, CXCR1, and CXCR4 expression was restricted to few tumor cells. Radiation caused up- and down-regulation with respect to chemokine expressions, while for chemokine receptor expressions down-regulations were prevailing. CXCL1 and CXCL12 protein expression corresponded well with the mRNA expression. We conclude that the substantial variation in chemokine and chemokine receptor expression between SCCHN offer opportunities for the establishment of assays to test for the relevance of chemokine and chemokine receptor expression in the response of SCCHN to radiotherapy and radiochemotherapy.