Neutrophil-activating peptide 1/interleukin 8 mRNA expression and protein secretion by human monocytes: effect of cyclosporin A

Neutrophil-activating peptide 1/interleukin 8 (NAP-1/IL-8) is a recently described cytokine with potent chemotactic activity for human neutrophil granulocytes (PMN) and T cells. In psoriasis, a chronic hyperproliferative and inflammatory skin disorder, PMN and T cells are found as prominent cells in the inflammatory infiltrate of the lesions; however, monocytes were shown to be the first cells invading a newly formed plaque. NAP-1/IL-8 was found to be present in high amounts in the skin and in scale material of psoriatic patients. Psoriasis responds well to systemic treatment with cyclosporin A (CsA), an immunosuppressive peptide. Therefore, we addressed the question of whether the clinical improvement of psoriatic patients during CsA therapy may be due to an inhibition of NAP-1/IL-8 production and secretion from monocytes. Purified human monocytes were stimulated by lipopolysaccharide in the presence or absence of various concentrations of CsA. Production of NAP-1/IL-8 was determined as expression of specific mRNA by fluorescent in situ hybridization. Secreted peptide was measured by bioassay (PMN chemotaxis) and enzyme-linked immunosorbent assay (ELISA) using specific monoclonal antibodies. The results show that CsA neither inhibited mRNA expression for NAP-1/IL-8 nor secretion of the peptide. These findings support the hypothesis that the pharmacological effect of CsA may be restricted to the inhibition of T-cell activation and proliferation.

Localization of neutrophil-activating peptide-1/interleukin-8-immunoreactivity in normal and psoriatic skin

Various cytokines have in the past been detected in human skin. Among these, the neutrophil-activating peptide NAP-1/IL-8 is a potent 8-kD proinflammatory peptide that has been purified from psoriatic scales. Its chemotactic activity on human neutrophils, as well as its presence in psoriatic scales, may relate to a role in this disease. In the present study, the tissue distribution of the peptide was examined immunohistochemically using two monoclonal antibodies (52E8, 46E5) recently produced and characterized in our laboratory. Immunoreactivity was detected in both normal and psoriatic skin, resulting in uniform suprabasal keratinocyte staining in normal skin with 52E8 and of all keratinocytes with 46E5. Immunoreactivity in psoriasis correlated to the inflammatory tissue reaction, varying from uniform absence in highly active psoriasis to focally weak staining in plaque type psoriasis. Cells of the acrosyringium and hair follicles were always positive and were unaffected by the inflammatory activity. Epidermal immunoreactivity detected in this study may be associated with closely related peptides of the IL8 family or with truncated or extended forms of NAP-1/IL-8.

Identification of a novel platelet-derived neutrophil-chemotactic polypeptide with structural homology to platelet-factor 4

A novel protein, NAP-4, could be isolated from human platelet lysates. NAP-4 preparations induced chemotaxis of human neutrophils with an ED50 near 400 ng/ml. Purification by anti NAP-1/IL-8 affinity chromatography and reversed phase HPLC revealed a single peak showing a single line upon SDS-PAGE corresponding to a Mr of 8000. NH2-terminal sequence analysis indicated an unique sequence showing strong homology to human platelet factor 4 and weak homology to tumor necrosis factor alpha as well. The most interesting finding is the absence of the first two cysteins, known to be strongly conserved in members of the family of platelet-factor 4-like host defense cytokines.

IL-1 alpha or tumor necrosis factor-alpha stimulate release of three NAP-1/IL-8-related neutrophil chemotactic proteins in human dermal fibroblasts

Human dermal fibroblasts in culture secrete three protein-like neutrophil chemotactic factors, when stimulated either with human rIL-1 alpha or IL-1 beta; not, however, after incubation with LPS. These three fibroblast-derived neutrophil-activating proteins (FINAP) could be purified by subsequently performed reversed phase and size exclusion HPLC. By high resolution SDS-PAGE, all the proteins were shown to migrate with an Mr of 6,700 (alpha-FINAP), 3,600 (beta-FINAP), and 5,300 (gamma-FINAP). All purified cytokine preparations were found to be chemotactic for human neutrophils. In addition, all FINAP induced release of lysosomal enzymes in neutrophils. Deactivation of chemotaxin-elicitable enzyme release showed cross-desensitization of all FINAP with NAP-1/IL-8. Western blot analysis of alpha-FINAP by using mAb against neutrophil-activating protein (NAP)-1/IL-8 reveals immunologic cross-reactivity with NAP-1/IL-8. By amino-terminal amino acid sequence analysis alpha-FINAP could be identified as the 77-residue extended form of NAP-1/IL-8 containing the 79-residue form as a minor contaminant. Whereas beta-FINAP has been found to be a truncation product of alpha-FINAP, gamma-FINAP shows identity with authentic melanoma growth stimulatory activity with respect to retention time upon reversed phase HPLC, high resolution SDS-PAGE, and biologic properties, as well as amino-terminal amino acid sequence. These data show that human dermal fibroblasts may actively participate in inflammatory reactions by secretion of proinflammatory cytokines.

IL-1 alpha or tumor necrosis factor-alpha stimulate release of three NAP-1/IL-8-related neutrophil chemotactic proteins in human dermal fibroblasts

Human dermal fibroblasts in culture secrete three protein-like neutrophil chemotactic factors, when stimulated either with human rIL-1 alpha or IL-1 beta; not, however, after incubation with LPS. These three fibroblast-derived neutrophil-activating proteins (FINAP) could be purified by subsequently performed reversed phase and size exclusion HPLC. By high resolution SDS-PAGE, all the proteins were shown to migrate with an Mr of 6,700 (alpha-FINAP), 3,600 (beta-FINAP), and 5,300 (gamma-FINAP). All purified cytokine preparations were found to be chemotactic for human neutrophils. In addition, all FINAP induced release of lysosomal enzymes in neutrophils. Deactivation of chemotaxin-elicitable enzyme release showed cross-desensitization of all FINAP with NAP-1/IL-8. Western blot analysis of alpha-FINAP by using mAb against neutrophil-activating protein (NAP)-1/IL-8 reveals immunologic cross-reactivity with NAP-1/IL-8. By amino-terminal amino acid sequence analysis alpha-FINAP could be identified as the 77-residue extended form of NAP-1/IL-8 containing the 79-residue form as a minor contaminant. Whereas beta-FINAP has been found to be a truncation product of alpha-FINAP, gamma-FINAP shows identity with authentic melanoma growth stimulatory activity with respect to retention time upon reversed phase HPLC, high resolution SDS-PAGE, and biologic properties, as well as amino-terminal amino acid sequence. These data show that human dermal fibroblasts may actively participate in inflammatory reactions by secretion of proinflammatory cytokines.

Detection of neutrophil-activating peptide NAP/IL-8 and NAP/IL-8 mRNA in human recombinant IL-1 alpha- and human recombinant tumor necrosis factor-alpha-stimulated human dermal fibroblasts. An immunocytochemical and fluorescent in situ hybridization study

A neutrophil-activating peptide (NAP)/IL-8 produced by LPS-stimulated human peripheral blood monocytes was biochemically purified and functionally characterized by different investigators. Work conducted in our laboratory showed that NAP/IL-8 as well as variants of this peptide are produced by a variety of cells (e.g., monocytes, T lymphocytes, endothelial cells) and that lesional psoriatic scales contain large amounts of biologically active NAP/IL-8. We now investigated human dermal fibroblasts for production of NAP/IL-8. The peptide was detected by immunocytochemistry by using the mAb 46E5. NAP/IL-8 mRNA was visualized by high resolutive fluorescent in situ hybridization with biotinylated antisense/sense RNA probes. Among the various stimuli used [human (h)rIL-1 alpha, hrTNF-alpha, hrIL-3, hr-granulocyte-macrophage-CSF, LPS, FMLP, and platelet-activating factor (PAF)] only hrIL-1 alpha (100 U/ml) and hrTNF-alpha (100 ng/ml) induced the transcription and translation of NAP/IL-8. In contrast to monocytes, LPS was without effect in cultured human dermal fibroblasts. Both NAP/IL-8 and NAP/IL-8 mRNA were found in the cytoplasm adjacent to the nucleus, but interestingly NAP/IL-8 mRNA was not restricted to the cytoplasm. In positive cells only two small bright spots were randomly distributed in the nucleus. Most likely these spots represent transcription sites where NAP/IL-8 mRNA is accumulated during gene expression. Our observations show that stimulation of dermal fibroblasts with the cytokines hrIL-1 alpha and hrTNF-alpha results in expression of IL-8.

Detection of neutrophil-activating peptide NAP/IL-8 and NAP/IL-8 mRNA in human recombinant IL-1 alpha- and human recombinant tumor necrosis factor-alpha-stimulated human dermal fibroblasts. An immunocytochemical and fluorescent in situ hybridization study

A neutrophil-activating peptide (NAP)/IL-8 produced by LPS-stimulated human peripheral blood monocytes was biochemically purified and functionally characterized by different investigators. Work conducted in our laboratory showed that NAP/IL-8 as well as variants of this peptide are produced by a variety of cells (e.g., monocytes, T lymphocytes, endothelial cells) and that lesional psoriatic scales contain large amounts of biologically active NAP/IL-8. We now investigated human dermal fibroblasts for production of NAP/IL-8. The peptide was detected by immunocytochemistry by using the mAb 46E5. NAP/IL-8 mRNA was visualized by high resolutive fluorescent in situ hybridization with biotinylated antisense/sense RNA probes. Among the various stimuli used [human (h)rIL-1 alpha, hrTNF-alpha, hrIL-3, hr-granulocyte-macrophage-CSF, LPS, FMLP, and platelet-activating factor (PAF)] only hrIL-1 alpha (100 U/ml) and hrTNF-alpha (100 ng/ml) induced the transcription and translation of NAP/IL-8. In contrast to monocytes, LPS was without effect in cultured human dermal fibroblasts. Both NAP/IL-8 and NAP/IL-8 mRNA were found in the cytoplasm adjacent to the nucleus, but interestingly NAP/IL-8 mRNA was not restricted to the cytoplasm. In positive cells only two small bright spots were randomly distributed in the nucleus. Most likely these spots represent transcription sites where NAP/IL-8 mRNA is accumulated during gene expression. Our observations show that stimulation of dermal fibroblasts with the cytokines hrIL-1 alpha and hrTNF-alpha results in expression of IL-8.

Production and characterization of monoclonal antibodies against the novel neutrophil activating peptide NAP/IL-8

LPS-stimulated human mononuclear cells have recently been shown to produce large amounts of a novel neutrophil-activating cytokine termed neutrophil-activating peptide NAP/IL-8. This chemotactic factor has in the meantime been biochemically and functionally well characterized. We now report on four distinct murine mAb directed against this peptide. All four mAb are different in respect to isotype and IEF pattern. The cross-reactivity with partially homologous peptides like beta-thromboglobulin and platelet factor 4 showed defined differences. With the use of these antibodies we were able to detect solid phase as well as soluble NAP/IL-8 as tested in a sandwich-ELISA. Also dose-dependent neutralization of NAP/IL-8 chemotactic activity in the Boyden chamber chemotaxis assay was observed. Immunoaffinity columns prepared with these four mAb bound NAP/IL-8 from supernatants of LPS-stimulated mononuclear cells. Furthermore, Western immunoblots showed a single protein band in the expected region of Mr of 10 kDa with all four mAb presented.

Production and characterization of monoclonal antibodies against the novel neutrophil activating peptide NAP/IL-8

LPS-stimulated human mononuclear cells have recently been shown to produce large amounts of a novel neutrophil-activating cytokine termed neutrophil-activating peptide NAP/IL-8. This chemotactic factor has in the meantime been biochemically and functionally well characterized. We now report on four distinct murine mAb directed against this peptide. All four mAb are different in respect to isotype and IEF pattern. The cross-reactivity with partially homologous peptides like beta-thromboglobulin and platelet factor 4 showed defined differences. With the use of these antibodies we were able to detect solid phase as well as soluble NAP/IL-8 as tested in a sandwich-ELISA. Also dose-dependent neutralization of NAP/IL-8 chemotactic activity in the Boyden chamber chemotaxis assay was observed. Immunoaffinity columns prepared with these four mAb bound NAP/IL-8 from supernatants of LPS-stimulated mononuclear cells. Furthermore, Western immunoblots showed a single protein band in the expected region of Mr of 10 kDa with all four mAb presented.