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It is widely accepted that neurokinin 1 (NK1) receptors are not generally expressed on mast cells but little is known about their expression in inflammation. The present study shows expression of NK1 receptors on bone marrow-derived mast cells (BMMC) under the influence of IL-4 or stem cell factor (SCF). Highest expression was found when both cytokines are present. Six days of coculture with the cytokines IL-4 and SCF showed significant expression of NK1 receptors (NK1 receptor+/c-kit+ BMMC; control: 7%, IL-4/SCF: 16%), while 12 days of cytokine coculture increased this expression to 37% positive cells. A longer coculture with IL-4 and SCF did not give an additional effect. Increased expression in IL-4/SCF-treated BMMC was further confirmed using Western blot analysis. Next, we demonstrated the functional relevance of NK1 receptor expression for mast cell activation, resulting in an enhanced degranulation upon stimulation by substance P. BMMC activation was significantly diminished by the NK1 receptor antagonist RP67580 (10 μM) when stimulated with low concentrations of substance P. The inactive enantiomer RP65681 had no effect. In addition, BMMC cultured from bone marrow of NK1 receptor knockout mice showed significantly decreased exocytosis to low concentrations of substance P. The present study clearly shows that NK1 receptor-induced activation contributes significantly at low physiological substance P concentrations (<100 μM). In conclusion, BMMC were shown to express NK1 receptors upon IL-4/SCF coculture. This expression of NK1 receptors has been demonstrated to be of functional relevance and leads to an increase in the sensitivity of BMMC to substance P.

The Fc receptor family plays a key role in adaptive immunity through the binding of immunoglobulin antibodies that recognize an immune insult and elicit an inflammatory response leading to its clearance. Dysregulation of this receptor family may have untoward consequences that result in autoimmune and allergic diseases. Many of these diseases seem to involve the nervous system and are exacerbated by stress or other neurological challenges. Recently, the presence of Fc receptors was uncovered on dorsal root ganglion neurons and suggested an IgG and possibly IgE-mediated activation of neurons 1-3 . We set out to more extensively explore which Fc receptors might be expressed in neurons, and whether they were functional and able to transmit signals to interconnected neurites in vitro and in vivo Messenger RNA was isolated from a highly pure culture of mouse superior cervical ganglion (SCG) neurons 4 and expression of Fc receptor transcripts assessed by reverse transcriptasepolymerase chain reactions (RT-PCR) using specific primers for Fcγ and Fcε family members. Fig. 1,a demonstrates the presence of transcripts for the immunoglobulin-binding α chain of FcγRI, II, III, and IV in three individual SCG neuron mRNA preparations. A small amount of the transcript for the low affinity IgE receptor (FcεRII or CD23) was also detected relative to Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. that seen in B cells, known to express this receptor. FcγRI transcripts were detected in bone marrow derived mouse mast cells but these levels were less than seen in the neurons. This observation and the inability to detect mMCP-6mRNA in either Balb/c or Bl6 mice, together with the absence of CD23 transcripts in both neurons and mast cells provided confidence that the observed Fc receptor transcripts in neurons was not a result of mast cell contamination of cultures. NIH Public AccessWe also unexpectedly observed the presence of transcripts for the α, β, and γ chains of the high affinity IgE receptor (FcεRI) (Fig. 1,b). While the trimeric form (αγ 2 ) of this receptor has been described in cells other than mast cells or basophils (such as in human Langerhans cells 5), the expression of the tetrameric form (αβγ 2 ) was previously thought to be limited to these proinflammatory cells. The trimeric FcεRI shows weak calcium signals when compared to the tetrameric form due to the absence of the FcεRIβ in the former 6 . To determine if the FcεRI was expressed on the cell surface of SCG neurons, cells were incubated with IgE and with an antibody to the neuronal specific protein gene product (PGP) 9.5 (whi...

The mechanisms involved in nonatopic asthma are poorly defined. In particular, the importance of mast cells in the development of nonatopic asthma is not clear. In the mouse, pulmonary hypersensitivity reactions induced by skin sensitization with the low-m.w. compound dinitrofluorobenzene (DNFB) followed by an intra-airway application of the hapten have been featured as a model for nonatopic asthma. In present study, we used this model to examine the role of mast cells in the pathogenesis of nonatopic asthma. First, the effect of DNFB sensitization and intra-airway challenge with dinitrobenzene sulfonic acid (DNS) on mast cell activation was monitored during the early phase of the response in BALB/c mice. Second, mast cell-deficient W/Wv and Sl/Sld mice and their respective normal (+/+) littermate mice and mast cell-reconstituted W/Wv mice (bone marrow-derived mast cells→W/Wv) were used. Early phase mast cell activation was found, which was maximal 30 min after DNS challenge in DNFB-sensitized BALB/c, +/+ mice but not in mast cell-deficient mice. An acute bronchoconstriction and increase in vascular permeability accompanied the early phase mast cell activation. BALB/c, +/+ and bone marrow-derived mast cell→W/Wv mice sensitized with DNFB and DNS-challenged exhibited tracheal hyperreactivity 24 and 48 h after the challenge when compared with vehicle-treated mice. Mucosal exudation and infiltration of neutrophils in bronchoalveolar lavage fluid associated the late phase response. Both mast cell-deficient strains failed to show any features of this hypersensitivity response. Our findings show that mast cells play a key role in the regulation of pulmonary hypersensitivity responses in this murine model for nonatopic asthma.

More and more studies are demonstrating interactions between the nervous system and the immune system. However, the functional relevance of this interaction still remains to be elucidated. Such associations have been found in the intestine between nerves and mast cells as well as between eosinophils and plasma cells. Similar morphologic associations have been demonstrated in the liver, mesentery, urinary bladder, and skin. Unmyelinated axons especially were found to associate with mast cells as well as Langerhans' cells in primate as well as murine skin. Although there are several pathways by which immune cells interact with the nervous system, the focus in this review will be on the interaction between mast cells and nerves.

Upon daily intragastric exposure to food allergens, the specificities of the induced antibody responses in the BN rat resemble those found in food-allergic patients. These studies add further support to the hypothesis that the BN rat may provide a suitable animal model for food allergy research and research on the allergenicity of food proteins.

Background: Suppression of Th2 cytokine production by allergen-specific Th2 cells is considered to be critical for the suppression of allergic symptoms by subcutaneous immunotherapy. The aim of this study was to develop a mouse model for birch pollen (BP) immunotherapy to elucidate the underlying mechanisms that contribute to the improvement of clinical symptoms. Methods: Mice with BP-induced allergic airway inflammation received weekly subcutaneous immunotherapy (SCIT) injections with BP extract (BPE) adsorbed to alum. The effect of an increasing dose of BPE adsorbed to a fixed concentration of alum on the suppression of airway inflammation and airway hyper-responsiveness (AHR) was determined. After 2, 4, 6 or 8 immunotherapy injections, the mice were rechallenged with the same allergen and all hallmarks of allergic asthma were evaluated. Results: Suppression of the immunological parameters by immunotherapy was dependent on the BPE dose. Two injections were sufficient to suppress IL-4, IL-5, IL-13, IL-10 and IFN-G production, eosinophil recruitment and peribronchial inflammatory infiltrates. BP-specific immunoglobulins were upregulated, but this was not sufficient to reduce AHR. Eight injections were needed to suppress AHR. The gradual reduction in AHR was inversely associated with the increase of BP IgG2a. Conclusions: BP SCIT induces an early suppression of Th2-mediated eosinophilic airway inflammation, but AHR is only effectively reduced after continued SCIT conceivably by allowing IgG2a antibody titres to build up. i 2014 S. Karger AG, Basel

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