Siramesine causes preferential apoptosis of mast cells in skin biopsies from psoriatic lesions.

BACKGROUND: Skin mast cells are implicated as detrimental effector cells in various inflammatory skin diseases such as contact eczema, atopic dermatitis and psoriasis. Selective reduction of cutaneous mast cells, e.g. by inducing targeted apoptosis, might prove a rational and efficient therapeutic strategy in dermatoses negatively influenced by mast cells. OBJECTIVES: The objective of the present study was to evaluate whether a lysosomotropic agent such as siramesine can cause apoptosis of mast cells present in psoriatic lesions. MATERIALS AND METHODS: Punch biopsies were obtained from lesional and uninvolved skin in 25 patients with chronic plaque psoriasis. After incubation with siramesine, the number of tryptase-positive mast cells and their expression of interleukin (IL)-6 and IL-17 was analysed. Skin biopsies were digested to allow flow cytometric analysis of the drug's effect on cutaneous fibroblasts and keratinocytes. RESULTS: Siramesine caused a profound reduction in the total number of mast cells in both lesional and uninvolved psoriatic skin biopsies without affecting the gross morphology of the tissue. The drug reduced the density of IL-6- and IL-17-positive mast cells, and showed antiproliferative effects on epidermal keratinocytes but had no apparent cytotoxic effect on keratinocytes or dermal fibroblasts. CONCLUSIONS: Considering the pathophysiology of psoriasis, the effects of siramesine on cutaneous mast cells may prove favourable from the therapeutic aspect. The results encourage further studies to assess the usefulness of siramesine and other lysosomotropic agents in the treatment of cutaneous mastocytoses and inflammatory skin diseases aggravated by dermal mast cells.

A key requirement for CD300f in innate immune responses of eosinophils in colitis.

Eosinophils are traditionally studied in the context of type 2 immune responses. However, recent studies highlight key innate immune functions for eosinophils especially in colonic inflammation. Surprisingly, molecular pathways regulating innate immune activities of eosinophil are largely unknown. We have recently shown that the CD300f is highly expressed by colonic eosinophils. Nonetheless, the role of CD300f in governing innate immune eosinophil activities is ill-defined. RNA sequencing of 162 pediatric Crohn's disease patients revealed upregulation of multiple Cd300 family members, which correlated with the presence of severe ulcerations and inflammation. Increased expression of CD300 family receptors was also observed in active ulcerative colitis (UC) and in mice following induction of experimental colitis. Specifically, the expression of CD300f was dynamically regulated in monocytes and eosinophils. Dextran sodium sulfate (DSS)-treated Cd300f-/- mice exhibit attenuated disease activity and histopathology in comparison with DSS-treated wild type (WT). Decreased disease activity in Cd300f-/- mice was accompanied with reduced inflammatory cell infiltration and nearly abolished production of pro-inflammatory cytokines. Monocyte depletion and chimeric bone marrow transfer experiments revealed a cell-specific requirement for CD300f in innate immune activation of eosinophils. Collectively, we uncover a new pathway regulating innate immune activities of eosinophils, a finding with significant implications in eosinophil-associated gastrointestinal diseases.

Eosinophil granulocytes are activated during the remission phase of ulcerative colitis.

AIM: The aim of this study was to establish a method of investigating intestinal eosinophil and neutrophil granulocytes by flow cytometry, and to compare the distribution and activity of these cells in different stages of ulcerative colitis (UC). METHODS: Biopsy samples were taken from six locations of the entire colon and from the terminal ileum in 10 patients with active total UC, 10 patients with inactive total UC, eight patients with active distal UC, and 11 control subjects. Cell suspensions from biopsies and from peripheral blood were incubated with fluorophore conjugated monoclonal antibodies. The use of scatter plot-gating and specific antibodies was established in a flow cytometry assay. RESULTS: Eosinophils were more numerous and more active in patients with active UC than in controls. Interestingly, during inactive UC, the number of activated eosinophils was even larger. Eosinophil activity was high in the rectum of patients with distal colitis but was also slightly elevated in the proximal colon. Neutrophils were increased in number and activity during active but not inactive UC. In patients with distal colitis, activated neutrophils were only found in the sigmoid colon and rectum. CONCLUSION: With this method, we confirm that neutrophils participate in the inflammatory process during active UC, and that they express a resting phenotype during remission. The finding of activated eosinophils in inflamed intestine strengthens the view of these cells as proinflammatory and tissue damaging. Nevertheless, our new finding of high eosinophil activation during inactive UC suggests that eosinophils play a role in repair of injured epithelium.

Cytokine-regulated accumulation of eosinophils in inflammatory disease.

The role of cytokines in the accumulation of eosinophil granulocytes in inflamed tissue has been studied extensively during recent years, and these molecules have been found to participate throughout the whole process of eosinophil recruitment. Haematopoietic cytokines such as IL-3, IL-5 and GM-CSF stimulate the proliferation and differentiation of eosinophils in the bone marrow, and the release of mature eosinophils from the bone marrow into the blood is probably promoted by IL-5. Priming of eosinophils in the blood following, for example, allergen challenge is performed mainly by IL-3, IL-5 and GM-CSF. An important step in the extravasation of eosinophils is their adhesion to the vascular endothelium. Adhesion molecules are upregulated by, e.g. IL-1, IL-4, TNF-alpha and IFN-gamma and the same cytokines may also increase the affinity of adhesion molecules both on eosinophils and endothelial cells. Finally, a number of cytokines have been shown to act as eosinophil chemotactic factors, attracting the cells to the inflammatory focus in the tissue. Some of the most important eosinophil chemoattractant cytokines are IL-5, IL-8, RANTES, eotaxin, eotaxin-2, eotaxin-3, MCP-3, MCP-4 and TNF-alpha. Th2 cells, mast cells and epithelial cells are important sources of proinflammatory cytokines, but in recent years, the eosinophils have also been recognized as cytokine-producing and thereby immunoregulatory cells. The aim of this paper is to review the role of cytokines in the process of eosinophil recruitment in asthma, allergy and ulcerative colitis.

IL-5 and TNF-alpha participate in recruitment of eosinophils to intestinal mucosa in ulcerative colitis.

There is an increased influx of activated eosinophils to the intestinal mucosa in active ulcerative colitis, and an increased release of eosinophil-derived proteins, such as ECP, has also been observed. These findings indicate that eosinophils may contribute to tissue damage and intestinal inflammation in this disease. The relative importance of different chemotactic factors and the impact of steroid treatment on their effect in active ulcerative colitis are not known. We measured the eosinophil chemotactic activity in perfusion fluids from 11 patients with ulcerative colitis before and after steroid treatment and from 7 control patients. The effect of neutralizing antibodies to IL-5 and -8, RANTES, eotaxin, MCP-3, TNF-alpha, GM-CSF was investigated. The chemotactic activity was higher in perfusion fluids from patients than from controls (P = 0.0043). Anti-IL-5 (P = 0.005) and -TNF-alpha (P = 0.017) inhibited the activity in perfusion fluids obtained before treatment. Steroid treatment prevented the effect of all antibodies but had no significant effect on the chemotactic activity. The chemotactic activity correlated with the levels of eosinophil granule proteins in the perfusion fluids. In conclusion, in ulcerative colitis, eosinophils are attracted to the intestinal tissue by chemotactic factors, of which IL-5 and TNF-alpha may be the most prominent steroid-sensitive ones. The steroid-insensitive chemotactic activities remain unidentified.

Interleukin-2 inhibits eosinophil migration but is counteracted by IL-5 priming.

Conflicting data on the role of interleukin-2 in the recruitment of eosinophil granulocytes (EOS) to sites of inflammation have been presented. The objective of the present study was to investigate the effect of recombinant human IL-2 and anti-IL-2 on the migration of purified blood EOS. Neutralizing antibodies to IL-2 were added to a cytokine mixture with significant eosinophil chemotactic activity (ECA), and afterwards the ECA was tested on EOS from both normal and allergic donors. EOS migration was measured by a modification of the Boyden technique, using a 48-well microchemotaxis chamber. Recombinant human IL-2 was either added to the lower compartment of the chemotaxis chamber, or to the EOS for a pre-incubation period of 20 min, before migration assays towards the chemotaxins were performed. Anti-IL-2 caused a significant increase of EOS migration towards the cytokine mixture. Pre-incubation of the EOS with rhIL-2 inhibited the chemotaxis towards RANTES, PAF, IL-8 and eotaxin, and EOS migration towards IL-2 was lower than that towards buffer. These effects were more pronounced on EOS from normal than from allergic donors. Priming of the EOS with IL-5 prevented the inhibitory effect of IL-2. We hypothesize that IL-2 acts as an autocrine regulator of EOS migration, and that this inhibitory effect may be downregulated in allergy, allowing an increased migration of EOS towards chemotactic factors.

The role of interleukin-5, interleukin-8 and RANTES in the chemotactic attraction of eosinophils to the allergic lung.

BACKGROUND: Bronchoalveolar lavage (BAL) fluid from patients with birch-pollen allergy lavaged during the season showed an elevated chemotactic activity for eosinophils compared with BAL fluid from the same patients before the start of the season. AIM: The aim of this study was to identify the eosinophil chemotactic agents in the BAL fluid, to compare these findings with in vitro studies on selected cytokines, and to investigate the interactions between these cytokines. METHODS: Neutralizing antibodies for interleukins (IL) -2, -5 and -8, RANTES and leukaemia inhibitory factor (LIF) were added to the BAL fluid, and the chemotactic activity was tested with eosinophils from allergic donors. Eosinophils from healthy donors were preincubated with IL-5 in order to mimic the primed state of eosinophils from allergics, and the migration towards recombinant IL-5, IL-8, and RANTES in different combinations was measured. Eosinophils from allergic donors were also used. RESULTS: Anti-IL-5, anti-IL-8 and anti-RANTES inhibited the chemotactic activity in the BAL fluid. Recombinant RANTES induced migration, which was enhanced by preincubation of the cells with IL-5. Only eosinophils from symptomatic allergics responded to IL-8, and IL-5 was not sufficient to prime normal eosinophils in vitro to an IL-8 response. A negative correlation was found between the level of in vivo activation of the cells and their response to IL-5, and a positive correlation with the response to RANTES. CONCLUSION: IL-8 and RANTES are important for eosinophil accumulation to the lung of pollen-allergic asthmatics. IL-5 alone may not be responsible for the priming of eosinophils in vivo, but is an essential cofactor for the other chemoattractants.

Disulfide bonding and cysteine accessibility in the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor subunit GluRD. Implications for redox modulation of glutamate receptors.

Redox agents elicit a wide variety of effects on the ligand affinity and channel properties of ionotropic glutamate receptors and have been proposed as potential therapeutic agents for neuropathological processes. One such effect is the dithiothreitol (DTT)-induced increase in agonist affinity of certain ionotropic glutamate receptors (GluRs), presumably due to reduction of a disulfide bridge formed between cysteine residues conserved among all GluRs. Using biochemical techniques, this disulfide is shown to exist in the ligand-binding domain of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor subunit GluRD, although GluRD homomeric receptors are not modulated by DTT. The disulfide is inaccessible to DTT, explaining the insensitivity of the intact receptor. Single mutants C260S and C315S show a 2-3-fold higher ligand affinity than wild-type, as observed for several intact GluRs, indicating that the affinity switch is completely contained within the ligand-binding domain. Also, mutants lacking the native disulfide show non-native oligomerization and dramatically reduced specific activity. These facts suggest that the disulfide bridge is required for the stability of the ligand-binding domain, explaining its conservation. A third cysteine residue in the ligand-binding domain exists as a free thiol, partially sequestered in a hydrophobic environment. These results provide a framework for interpreting a variety of GluR redox modulatory phenomena.

AMPA receptors and bacterial periplasmic amino acid-binding proteins share the ionic mechanism of ligand recognition.

In order to identify key structural determinants for ligand recognition, we subjected the ligand-binding domain of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-selective glutamate receptor GluR-D subunit to site-directed mutagenesis. Based on the analysis of the [3H]AMPA-binding properties of the mutated binding sites, we constructed a revised three-dimensional model of the ligand-binding site, different in many respects from previously published models. In particular, our results indicate that the residues Arg507 and Glu727 represent the structural and functional correlates of Arg77 and Asp161 in the homologous bacterial lysine/ornithine/arginine-binding protein and histidine-binding protein, and directly interact with the alpha-carboxyl and alpha-amino group of the bound ligand, respectively. In contrast, Glu424, implicated previously in ionic interactions with the alpha-amino group of the agonist, is unlikely to have such a role in ligand binding. Our results indicate that glutamate receptors share with the bacterial polar amino acid-binding proteins the fundamental mechanism of amino acid recognition.

Identification of IL-5 and RANTES as the major eosinophil chemoattractants in the asthmatic lung.

The study was carried out to identify those molecules that are important in vivo in the attraction of eosinophil granulocytes to the lungs of patients with asthma. Asthmatic patients with birch pollen allergy had lavages performed before and during the pollen season, and the chemotactic activity of the bronchoalveolar lavage fluid was tested against normal eosinophils. The activity was significantly increased during the pollen season as compared with the activity before the pollen season (p less than 0.01). Neutralizing antibodies to IL-2, IL-5 and IL-8, leukemia inhibitory factor, and to RANTES were added to the bronchoalveolar lavage fluid. Antibodies to IL-5 and RANTES, but not to IL-2 and IL-8 or leukemia inhibitory factor, significantly inhibited the chemotactic activity for eosinophils (p less than 0.001). It is concluded that IL-5 and RANTES are important chemoattractants in the lungs of patients with allergic asthma. The effect of IL-5 may be that of a cofactor to the chemotactic molecules, of which RANTES may be one of the most important in allergic asthma.

Reflection and transmission measurements with an integrating sphere and Fourier-transform infrared spectrometer.

A method of measuring the total reflection and transmission spectra of scattering materials with an integrating sphere and a Fourier-transform infrared spectrometer is studied. The reflectance measurement system is considered in a specific case where the incident beam overfills the back side port of the sphere, and the correction functions for measured spectra are derived for this case. Correction formulas are based on the energy balance between incident radiation and absorbed or escaped radiation in the system. The absorption spectrum of the material is calculated from the corrected spectra. The optical properties of paper samples and radiating surfaces of infrared dryers in the 0.4-20-microm wavelength range are determined. The correction formulas are compared with previous work presented in the literature.

Yersiniosis as a gastrointestinal disease.

Anti-yersinia antibodies were assessed in sera from 630 patients admitted to a department of surgery for acute abdominal disease, using an enzyme-linked immunosorbent assay (ELISA). In 21 patients a high concentration of yersinia antibodies confirmed recent yersinia infection. Eight patients had an appendicectomy performed; in all patients with antibodies against Y. enterocolitica 9 or Y. pseudotuberculosis IA a true appendicitis was found at operation. Two patients with Y. enterocolitica 3 antibodies had acute terminal ileitis and mesenterial lymphadenitis. In 4 patients a diagnosis of acute pancreatitis was established; 2 of these had cholecystitis. Two further patients had cholecystitis without pancreatic affection. Two patients had colonic diverticulitis, 1 with perforation. The results demonstrate that yersinia infection may commonly give rise to a variety of acute abdominal inflammations, and stress the importance of serological and bacteriological diagnostic procedures.