Delayed production of biologically active O-glycosylated forms of human eotaxin by tumor-necrosis-factor-alpha-stimulated dermal fibroblasts

Since a number of inflammatory skin diseases are characterized by selective eosinophil infiltration preferentially in the dermis, we speculated that dermal fibroblasts might represent a potential cellular source of eosinophil-selective attractants. Cultivated dermal fibroblasts treated with tumor necrosis factor alpha secreted, not before day 3 of stimulation, eosinophil-specific chemotactic activity. Purification of this activity revealed a heparin-binding protein with an apparent molecular mass of 13 kDa in SDS/polyacrylamide gel electrophoresis. Peptide mapping with subsequent amino acid sequence analyses revealed it to be human eotaxin. Natural eotaxin preparations contain 50% N-terminally truncated forms missing two or three amino acids. It is O-glycosylated at Thr71, resulting in at least two sialylated O-glycosylated variants. Electrospray ionization mass spectrometric analyses revealed the natural eotaxin preparation to be heterogeneous with principal masses of 9033 Da and 9317 Da. Natural eotaxin stimulated eosinophil chemotaxis with identical potency and efficacy as recombinant human eotaxin. Neither neutrophils, monocytes or lymphocytes responded towards natural eotaxin preparations indicating that N-terminal truncation and O-glycosylation did not affect the cell-specificity of chemotactic activity. Treatment of eosinophils with natural eotaxin desensitizes chemotactic responses towards eotaxin, regulated an normal T-lymphocyte expressed and secreted (RANTES) and monocyte chemotactic protein 3 (MCP-3), whereas RANTES and MCP-3 were unable to desensitize natural eotaxin-dependent responses.

Human dermal fibroblasts express eotaxin: molecular cloning, mRNA expression, and identification of eotaxin sequence variants

Recently we discovered and purified a novel beta-chemokine with eosinophil specific chemotactic activity from supernatants to long-term TNF-alpha stimulated dermal fibroblasts. Using degenerated specific oligonucleotides based on partial amino acid sequence data and a PCR protocol, we obtained different clones sharing high sequence homology with this novel chemokine and with human eotaxin cDNA. Semi-quantitative RT-PCR experiments using eotaxin-specific primers indicate low constitutive eotaxin mRNA expression in human dermal fibroblasts which is upregulated by IL-1 alpha and TNF-alpha within 6 hrs and modulated by IFN-gamma. While IL-1 alpha-induced eotaxin mRNA accumulation is transient, long-term stimulation with TNF-alpha resulted in a further increase of eotaxin mRNA.

Eosinophil recruitment following allergen challenge is associated with the release of the chemokine RANTES into asthmatic airways

Eosinophil infiltration of the airways in response to allergen exposure is a characteristic of bronchial asthma. However, the mechanisms by which these cells are recruited are poorly understood. We have investigated the presence of eosinophil chemotactic activity (ECA) in bronchoalveolar lavage fluid obtained from allergic asthmatics (n = 6) 4 h after endobronchial allergen challenge. ECA was purified by sequential heparin affinity chromatography and reverse-phase HPLC. A single peak of ECA was detected; SDS-PAGE and Western blot analysis showed that the peak contained a protein of 8 kDa and corresponded to the chemokine RANTES (regulated upon activation, normal T cell expressed and secreted). Consistent with this, the ECA was neutralized by an Ab to RANTES. Measurement of RANTES by ELISA in 10x concentrated bronchoalveolar lavage fluid showed increased levels of this chemokine at the allergen site (median, 187 pg/ml; range, 46-263 pg/ml) in comparison with a saline challenge control site (median, 32.5 pg/ml; range, 11-94 pg/ml), P < 0.005. Furthermore, there was a significant correlation between concentrations of immunoreactive RANTES and the number of eosinophils at the allergen challenge site (r = 0.8; p < 0.001), but not at the saline site (r = 0.2; p = 0.12). These results suggest that RANTES in involved in the recruitment of eosinophils into the asthmatic airways after allergen challenge.

Eosinophil recruitment following allergen challenge is associated with the release of the chemokine RANTES into asthmatic airways

Eosinophil infiltration of the airways in response to allergen exposure is a characteristic of bronchial asthma. However, the mechanisms by which these cells are recruited are poorly understood. We have investigated the presence of eosinophil chemotactic activity (ECA) in bronchoalveolar lavage fluid obtained from allergic asthmatics (n = 6) 4 h after endobronchial allergen challenge. ECA was purified by sequential heparin affinity chromatography and reverse-phase HPLC. A single peak of ECA was detected; SDS-PAGE and Western blot analysis showed that the peak contained a protein of 8 kDa and corresponded to the chemokine RANTES (regulated upon activation, normal T cell expressed and secreted). Consistent with this, the ECA was neutralized by an Ab to RANTES. Measurement of RANTES by ELISA in 10x concentrated bronchoalveolar lavage fluid showed increased levels of this chemokine at the allergen site (median, 187 pg/ml; range, 46-263 pg/ml) in comparison with a saline challenge control site (median, 32.5 pg/ml; range, 11-94 pg/ml), P &lt; 0.005. Furthermore, there was a significant correlation between concentrations of immunoreactive RANTES and the number of eosinophils at the allergen challenge site (r = 0.8; p &lt; 0.001), but not at the saline site (r = 0.2; p = 0.12). These results suggest that RANTES in involved in the recruitment of eosinophils into the asthmatic airways after allergen challenge.

Identification of an N-terminally truncated form of the chemokine RANTES and granulocyte-macrophage colony-stimulating factor as major eosinophil attractants released by cytokine-stimulated dermal fibroblasts

Eosinophil (Eo) granule proteins and, rarely, intact Eos represent a characteristic histopathologic feature of the dermal part of affected tissue in atopic dermatitis and some allergic reactions. Dermal fibroblasts are a rich source of cytokines and inflammatory mediators; therefore, we have investigated whether these cells release Eo chemoattractants when stimulated with different stimuli. Eo-chemotactic activity was detected after stimulation of cells with TNF-alpha and IL-1, but not when phorbol ester, PHA, or medium alone was used. Biochemical characterization of Eo-chemotactic activity in supernatants of NF-alpha-stimulated cells revealed both heparin-binding and nonbinding activity. HPLC purification with subsequent N-terminal sequencing and mass spectrometric analysis showed that the heparin-binding Eo-chemotactic peak corresponded to the chemokine [Tyr-RANTES]66 that also contained [Ser-RANTES]68 as contaminant, whereas the nonheparin-binding activity was identified as granulocyte-macrophage CSF (GM-CSF) by the use of neutralizing Abs. [Tyr-RANTES]66 was found to show identical behavior in the chemotaxis assay system with respect to potency and efficacy as natural [Ser-RANTES]68. These findings support the hypothesis that dermal fibroblasts can play an important role in the recruitment of Eo by release of the chemokine RANTES together with GM-CSF.

Identification of an N-terminally truncated form of the chemokine RANTES and granulocyte-macrophage colony-stimulating factor as major eosinophil attractants released by cytokine-stimulated dermal fibroblasts

Eosinophil (Eo) granule proteins and, rarely, intact Eos represent a characteristic histopathologic feature of the dermal part of affected tissue in atopic dermatitis and some allergic reactions. Dermal fibroblasts are a rich source of cytokines and inflammatory mediators; therefore, we have investigated whether these cells release Eo chemoattractants when stimulated with different stimuli. Eo-chemotactic activity was detected after stimulation of cells with TNF-alpha and IL-1, but not when phorbol ester, PHA, or medium alone was used. Biochemical characterization of Eo-chemotactic activity in supernatants of NF-alpha-stimulated cells revealed both heparin-binding and nonbinding activity. HPLC purification with subsequent N-terminal sequencing and mass spectrometric analysis showed that the heparin-binding Eo-chemotactic peak corresponded to the chemokine [Tyr-RANTES]66 that also contained [Ser-RANTES]68 as contaminant, whereas the nonheparin-binding activity was identified as granulocyte-macrophage CSF (GM-CSF) by the use of neutralizing Abs. [Tyr-RANTES]66 was found to show identical behavior in the chemotaxis assay system with respect to potency and efficacy as natural [Ser-RANTES]68. These findings support the hypothesis that dermal fibroblasts can play an important role in the recruitment of Eo by release of the chemokine RANTES together with GM-CSF.

Role of eosinophil-chemotactic C-C chemokines in cutaneous inflammation

In the dermal sites of atopic skin, eosinophil (Eo) granule protein or more rarely intact Eos represent a characteristic histological feature. We addressed the question of whether lesional scales of patients with various eosinophilic skin disorders contain Eo attractant and tried to characterize it biochemically. In scales of a patient with drug reaction, heparin-binding Eo attractants could be identified. High-performance liquid chromatographic analyses together with specific ELISA and Western blot analyses revealed identity with RANTES. No other heparin-binding Eo chemotaxin could be identified. HPLC analysis of pooled lesional scale extracts of patients with atopic dermatitis showed fractions containing only weak heparin-binding Eo-chemotactic activity, which, however, showed RANTES immunoreactivity. In experiments to elucidate the putative cellular origin of Eo-attracting chemokines in human skin we investigated supernatants of atopic skin we investigated supernatants of atopic skin-derived T lymphocytes as well as supernatants of stimulated dermal fibroblasts for Eo-chemotactic factors. Unexpectedly, we did not find any heparin-bound Eo attractants in supernatants of stimulated cultured atopic skin-derived T lymphocyte clones, whereas fibroblasts produced RANTES as well as granulocyte-macrophage colony-stimulating factor. Therefore, fibroblasts are likely source of eosinophil attractant cells, which could contribute to the Eo infiltrate. Selectivity of the infiltrate might come from selective induction of RANTES and/or induction of other as yet unidentified Eo-specific chemokines.

Human monocyte chemotactic proteins-2 and 3 (MCP-2 and MCP-3) attract human eosinophils and desensitize the chemotactic responses towards RANTES

When synthetic monocyte chemotactic proteins (MCPs) were tested in a Boyden chamber assay system for eosinophil-chemotactic properties using human eosinophils, MCP-3 was found to be a potent and efficient (percentage input migrating cells) attractant with an ED50 near 2-3 nM. MCP-2 was less potent, exhibiting half maximal chemotaxis at 40 nM. Cross desensitization experiments of eosinophil-chemotaxis revealed that both MCP-3 and MCP-2 desensitized autologous responses. In addition, pretreatment of human eosinophils with natural RANTES desensitized chemotaxis towards MCP-3 as well as MCP-2, whereas pretreatment of eosinophils with MCP-3 desensitized, apart from responses to MCP-3, also responses against RANTES and MCP-2. These findings indicate that possibly both MCP-3 and MCP-2 elicit chemotactic responses via the RANTES-receptor on eosinophils.

The effect of histamine on cultured endothelial cells. A study of the mechanism of increased vascular permeability

The role of endothelial cells in the histamine-induced vascular response was investigated using cultured endothelial cells obtained from human umbilical veins. A single population of histamine H1 receptors was detected in these cells by means of a [3H]mepyramine binding assay. Its Kd was 0.74 +/- 0.07 nM and Bmax was 41.4 +/- 8.68 fmol/mg protein. Actin filaments were distributed as dense bands at the margin of the cells and as sparse microfilament bundles traversing the center of the cells. Histamine caused a decrease in peripheral bands and an increase in longitudinal bands. The changes evoked by histamine were dose-dependent, related to the duration of incubation of the cells with histamine, and blocked by mepyramine, a histamine H1 receptor antagonist. The results suggest that the endothelial cells respond to histamine through the histamine H1 receptor. This may explain one of the mechanisms of histamine-induced vascular response including vascular permeability increase.

Histamine H1-receptor of vascular endothelial cells cultured from guinea pig skin

In this study, a new procedure for the cultivation of dermal vascular endothelial cells from guinea pig ear lobe was established, and specific binding of [3H]mepyramine to the cultured cell membranes was demonstrated. The vascular endothelial cells were successfully isolated from the dermis of guinea pig ear lobes by the intravenous injection of dispase. Guinea pig serum, as a supplementary component in culture medium, is more suitable for the culture of guinea pig dermal vascular endothelial cell than is fetal calf serum. The [3H]mepyramine binding study indicated the presence of a large number of H1-receptors on the membrane of dermal vascular endothelial cells of guinea pigs, suggesting the important role of endothelial cells in cutaneous reactions to histamine.