Analysing the eosinophil cationic protein - a clue to the function of the eosinophil granulocyte

Eosinophil granulocytes reside in respiratory mucosa including lungs, in the gastro-intestinal tract, and in lymphocyte associated organs, the thymus, lymph nodes and the spleen. In parasitic infections, atopic diseases such as atopic dermatitis and asthma, the numbers of the circulating eosinophils are frequently elevated. In conditions such as Hypereosinophilic Syndrome (HES) circulating eosinophil levels are even further raised. Although, eosinophils were identified more than hundred years ago, their roles in homeostasis and in disease still remain unclear. The most prominent feature of the eosinophils are their large secondary granules, each containing four basic proteins, the best known being the eosinophil cationic protein (ECP). This protein has been developed as a marker for eosinophilic disease and quantified in biological fluids including serum, bronchoalveolar lavage and nasal secretions. Elevated ECP levels are found in T helper lymphocyte type 2 (atopic) diseases such as allergic asthma and allergic rhinitis but also occasionally in other diseases such as bacterial sinusitis. ECP is a ribonuclease which has been attributed with cytotoxic, neurotoxic, fibrosis promoting and immune-regulatory functions. ECP regulates mucosal and immune cells and may directly act against helminth, bacterial and viral infections. The levels of ECP measured in disease in combination with the catalogue of known functions of the protein and its polymorphisms presented here will build a foundation for further speculations of the role of ECP, and ultimately the role of the eosinophil

Alveolar accumulation of fibronectin and hyaluronan precedes bleomycin-induced pulmonary fibrosis in the rat

The development of bleomycin-induced pulmonary fibrosis in rats was studied over a period of 30 days after an intratracheal instillation of bleomycin. Fibronectin was visualized in histological sections and quantified in bronchoalveolar lavage fluid (BALF) and related to simultaneous measurements of hyaluronan, collagen and albumin in BALF and/or lung tissue extracts. An increase in BALF fibronectin levels was noted after 3 days and the peak value a sixty fold increase was noted at day 7. Thereafter, the fibronectin levels declined and reached control values on day 21. A pronounced, patchily distributed staining for fibronectin appeared in the injured alveolar tissue parallel to the increased lavage fluid fibronectin levels on days 3-7. A fainter, streakily distributed fibronectin staining remained within the alveolar walls in areas with proliferating fibroblasts on days 14-30. Albumin in BALF increased to a peak level, 20 times control values, after 3 days and then rapidly declined. Thus, the ratio of fibronectin to albumin increased to a peak value of 43 times control values on day 7, indicating that plasma leakage cannot be the only source of the observed increase in lavage fibronectin. Lung tissue hydroxyproline increased between days 7 and 30, whereas extractable hyaluronan in lung tissue and bronchoalveolar lavage fluid peaked on days 3-7 and then gradually declined towards normal values on days 21-30. These data demonstrate that fibronectin accumulates in the alveolar tissue during the early inflammatory phase of the bleomycin-induced lung injury, parallelling hyaluronan accumulation and preceding the development of pulmonary fibrosis

Inner valence region of CO adsorbed on Pd(100)

The inner valence region of CO/Pd(100) p(2√2×√2)R45° has been studied by angular resolved photoemission at the Pd 4d Cooper minimum, and with resonant Auger spectroscopy at photon energies corresponding to the C 1s and O 1s x-ray absorption (XA) maxima of the unoccupied parts of the 2π*-Pd 4d hybrid (2πun). Previously unobserved inner valence states are revealed in the direct photoemission and are compared with resonant Auger results. The interpretation and assignment of the different spectral features to different main final state configurations are based on energy, symmetry and intensity arguments, as well as comparisons with previous results

The effect of eosinophils on collagen gel contraction and implications for tissue remodelling

Asthma is characterized by an eosinophilic inflammation and a subepithelial fibrosis in the airways. Eosinophils contain several cytotoxic substances, such as eosinophil cationic protein (ECP), which can promote inflammation and cause tissue damage. This has generated the hypothesis that eosinophils may drive remodelling of extracellular matrix (ECM). To investigate the role of eosinophils we used an in vitro model for remodelling, the three-dimensional collagen gel contraction assay. Two sources of eosinophils were used in this study, isolated human peripheral eosinophils (purity > 95%) and stimulated [interleukin (IL)-5, IL-3 and granulocyte macrophage–colony stimulating factor (GM-CSF)] HL-60 clone 15 cells. Human eosinophils or HL-60 cells were cast together with human lung fibroblasts (HFL1) in type I collagen gels. Both types of eosinophils augmented fibroblast-mediated collagen gel contraction in a time and concentration-dependent manner. At 48 h, the gel area in HFL1/eosinophil co-culture was 46·5% ± 0·5 (mean ± s.e.m.) of initial area and in HFL1 culture 52·3% ± 0·1 (P < 0·001). Respective figures for HFL1/stimulated HL-60 co-culture and HFL1 culture only were 44·1% ± 0·5 and 52·4% ± 0·4 (P < 0·001). The release of ECP was increased when fibroblasts were cultured with eosinophils compared to eosinophils cultured alone. In addition, native ECP added to fibroblast gel cultures also augmented contraction. Our results suggest that eosinophils may interact with mesenchymal cells, promoting remodelling of ECM and that ECP constitutes one potential eosinophil-derived mediator driving this process. We conclude that this may be one important mechanism by which eosinophil–ECM interactions will lead to airway tissue remodelling in asthma

Eosinophil granule-derived major basic protein induces IL-8 expression in human intestinal myofibroblasts

Eosinophil infiltration occurs in a variety of allergic and inflammatory diseases. The release of preformed mediators from eosinophils may contribute to inflammatory responses. We investigated the ability of eosinophil-derived major basic protein and eosinophil-derived neurotoxin to stimulate production of IL-8 from intestinal myofibroblasts. Intestinal myofibroblasts (18-Co cells) were incubated with major basic protein, eosinophil-derived neurotoxin, or a synthetic analogue of major basic protein, poly-l-arginine. Immunoreactive IL-8 was measured by ELISA and IL-8 mRNA levels were analysed by Northern blot or reverse transcription-polymerase chain assay. Major basic protein induced IL-8 mRNA production and release of significant levels of IL-8 immunoreactive protein. By contrast, eosinophil-derived neurotoxin stimulated little IL-8 release. The induction of IL-8 mRNA by poly-l-arginine was significantly inhibited by actinomycin D. These findings demonstrate a novel interaction between eosinophils and intestinal fibroblasts that may be involved in the pathogenesis of diseases associated with tissue eosinophilia