Identification and structural characterization of chemokines in lesional skin material of patients with inflammatory skin disease

Effect of Neferine on DNCB-Induced Atopic Dermatitis in HaCaT Cells and BALB/c Mice

Atopic dermatitis (AD) is a chronic and persistent inflammatory skin disease characterized by eczematous lesions and itching, and it has become a serious health problem. However, the common clinical treatments provide limited relief and are accompanied by adverse effects. Therefore, there is a need to develop novel and effective therapies to treat AD. Neferine is a small molecule compound isolated from the green embryo of the mature seeds of lotus (Nelumbo nucifera). It has a bisbenzylisoquinoline alkaloid structure. Relevant studies have shown that neferine has many pharmacological and biological activities, including anti-inflammatory, anti-thrombotic, and anti-diabetic activities. However, there are very few studies on neferine in the skin, especially the related effects on inflammatory skin diseases. In this study, we proved that it has the potential to be used in the treatment of atopic dermatitis. Through in vitro studies, we found that neferine inhibited the expression of cytokines and chemokines in TNF-α/IFN-γ-stimulated human keratinocyte (HaCaT) cells, and it reduced the phosphorylation of MAPK and the NF-κB signaling pathway. Through in vivo experiments, we used 2,4-dinitrochlorobenzene (DNCB) to induce atopic dermatitis-like skin inflammation in a mouse model. Our results show that neferine significantly decreased the skin barrier damage, scratching responses, and epidermal hyperplasia induced by DNCB. It significantly decreased transepidermal water loss (TEWL), erythema, blood flow, and ear thickness and increased surface skin hydration. Moreover, it also inhibited the expression of cytokines and the activation of signaling pathways. These results indicate that neferine has good potential as an alternative medicine for the treatment of atopic dermatitis or other skin-related inflammatory diseases.

Cationic Intrinsically Disordered Antimicrobial Peptides (CIDAMPs) Represent a New Paradigm of Innate Defense with a Potential for Novel Anti-Infectives

In the search for potential mechanisms underlying the remarkable resistance of healthy skin against infection by soil bacteria like Pseudomonas (P.) aeruginosa we identified fragments of the intrinsically disordered protein hornerin as potent microbicidal agents in the stratum corneum. We found that, independent of the amino acid (AA)-sequence, any tested linear cationic peptide containing a high percentage of disorder-promoting AA and a low percentage of order-promoting AA is a potent microbicidal antimicrobial. We further show that the antimicrobial activity of these cationic intrinsically disordered antimicrobial peptides (CIDAMPs) depends on the peptide chain length, its net charge, lipidation and environmental conditions. The ubiquitous presence of latent CIDAMP sources in nature suggests a common and yet overlooked adapted innate disinfection system of body surfaces. The simple structure and virtually any imaginable sequence or composition of disorder-promoting AA allow the generation of a plethora of CIDAMPs. These are potential novel microbicidal anti-infectives for various bacterial pathogens, including P. aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA) and fungal pathogens like Candida albicans and Cryptococcus neoformans.

Interleukin-8 content in the stratum corneum as an indicator of the severity of inflammation in the lesions of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is an inflammatory skin disease characterized by both acute and chronic eczema. Various markers are used to clinically evaluate the severity of AD. In order to identify a marker of local severity of AD, we measured IL-8, IL-18, vascular endothelial growth factor (VEGF), and transforming growth factor-α (TGF-α) levels in the stratum corneum (scIL-8, scIL-18, scVEGF and scTGF-α) and evaluated the correlation between the levels of these cytokines and the clinical severity scores of localized skin lesions.

METHODS

Stratum corneum samples were collected from the skin lesions of 50 patients with AD using the tape-stripping technique, and the scIL-8, scIL-18, scVEGF and scTGF-α levels were evaluated using the ELISA method. The trans-epidermal water loss and skin water content of the lesions were also measured prior to tape stripping.

RESULTS

The levels of scIL-8, scIL-18, scVEGF and scTGF-α were significantly higher in patients with AD than in healthy controls. Additionally, the levels of scIL-8, scIL-18 and scVEGF significantly correlated with the severity of AD.

CONCLUSIONS

Among these cytokines, scIL-8 showed the highest correlation with the severity scores of lesions in AD as well as other parameters. Our results also suggest that measuring cytokines in the stratum corneum by using ELISA combined with tape stripping is a convenient method to evaluate the severity of skin lesions in AD.

Uncovering the evolutionary history of innate immunity: the simple metazoan Hydra uses epithelial cells for host defence

Although many properties of the innate immune system are shared among multicellular animals, the evolutionary origin remains poorly understood. Here we characterize the innate immune system in Hydra, one of the simplest multicellular animals known. In the complete absence of both protective mechanical barriers and mobile phagocytes, Hydra's epithelium is remarkably well equipped with potent antimicrobial peptides to prevent pathogen infection. Induction of antimicrobial peptide production is mediated by the interaction of a leucine-rich repeats (LRRs) domain containing protein with a TIR-domain containing protein lacking LRRs. Conventional Toll-like receptors (TLRs) are absent in the Hydra genome. Our findings support the hypothesis that the epithelium represents the ancient system of host defence.

Identification of lympho-epithelial Kazal-type inhibitor 2 in human skin as a kallikrein-related peptidase 5-specific protease inhibitor

Kallikreins-related peptidases (KLKs) are serine proteases and have been implicated in the desquamation process of the skin. Their activity is tightly controlled by epidermal protease inhibitors like the lympho-epithelial Kazal-type inhibitor (LEKTI). Defects of the LEKTI-encoding gene serine protease inhibitor Kazal type (Spink)5 lead to the absence of LEKTI and result in the genodermatose Netherton syndrome, which mimics the common skin disease atopic dermatitis. Since many KLKs are expressed in human skin with KLK5 being considered as one of the most important KLKs in skin desquamation, we proposed that more inhibitors are present in human skin. Herein, we purified from human stratum corneum by HPLC techniques a new KLK5-inhibiting peptide encoded by a member of the Spink family, designated as Spink9 located on chromosome 5p33.1. This peptide is highly homologous to LEKTI and was termed LEKTI-2. Recombinant LEKTI-2 inhibited KLK5 but not KLK7, 14 or other serine proteases tested including trypsin, plasmin and thrombin. Spink9 mRNA expression was detected in human skin samples and in cultured keratinocytes. LEKTI-2 immune-expression was focally localized at the stratum granulosum and stratum corneum at palmar and plantar sites in close localization to KLK5. At sites of plantar hyperkeratosis, LEKTI-2 expression was increased. We suggest that LEKTI-2 contributes to the regulation of the desquamation process in human skin by specifically inhibiting KLK5.

Primary role of growth-related oncogene-alpha and granulocyte chemotactic protein-2 as neutrophil chemoattractants in chronic rhinosinusitis

BACKGROUND

The aetiology of chronic rhinosinusitis (CRS) remains unclear. The purpose of this study was to investigate neutrophil-attracting chemokine patterns in CRS without nasal polyposis.

METHODS

The biological activity of the chemokines was identified using a two-step high-performance liquid chromatography (HPLC) technique combined with a bioassay in extracts from 55 CRS patients, and in the turbinate mucosa (TM) of patients (N=51) undergoing septumplasty. The biologic activity of each chemokine was assessed using blocking antibodies to chemokines. Immunolocalization of detected neutrophil chemokines was performed by quantitative evaluation of immunohistochemistry. Besides, PCR analysis was performed to quantify neutrophil chemokine mRNA.

RESULTS

In CRS, the chemokines primarily detected by two-step HPLC were growth-related oncogene-alpha (GRO-alpha) and the granulocyte chemotactic protein-2 (GCP-2). Blocking of GCP-2 and GRO-alphad each resulted in chemotaxis inhibition rates of 43.3% and 35.9%, respectively, whereas anti-IL-8 and anti-ENA-78 had no effect. Both GCP-2 and GRO-alphad were generally synthesized by the surface epithelium and mucosal glands while GRO-alpha in particular was synthesized by endothelial cells, as shown by immunohistochemistry. The concentrations of the chemokines IL-8 and epithelial cell-derived neutrophil attractant-78 (ENA-78) were low in CRS and TM.

CONCLUSION

It appears that both GRO-alpha and GCP-2 contribute to neutrophil chemotaxis in CRS, whereas IL-8 and ENA-78 appear to be of secondary importance for the chemotaxis of neutrophils in this condition. The expression of chemokines in mucosal gland cells is the main phenomenon involved in constitutive neutrophil chemotaxis in the TM.

Neutrophil chemokines in epithelial inflammatory processes of human tonsils

CXC chemokines are thought to play an important role at sites of inflammation. Because ELR(+) CXC chemokines are expressed in different types of tonsillitis we investigated the role of the surface/crypt epithelium of human tonsils in producing ELR(+) CXC chemokines: interleukin (IL)-8 (CXCL8), ENA-78 (CXCL5), GRO-alpha (CXCL1) and GCP-2 (CXCL6). Tonsillar tissue was obtained from patients undergoing tonsillectomy and chemokine expression was investigated by means of immunohistochemistry. A549 cells were used as a model to study kinetics of chemokine expression in epithelial cells. Cells were stimulated with tumour necrosis factor (TNF)-alpha, lipopolysaccharide (LPS) and supernatants derived from aerobic/anaerobic Staphylococcus aureus strains. Chemokine expression was measured by quantitative reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). We observed epithelial expression of IL-8, GRO-alpha and GCP-2 in different types of tonsillitis, whereas ENA-78 was rarely expressed. In A549 cells abundant expression of ENA-78 was detected. IL-8 and GCP-2 are expressed in an acute type of tonsillitis whereas GRO-alpha was frequently detectable both in chronically and acutely inflamed tonsils. ENA-78 does not seem to play a pivotal role in tonsillitis in vivo.

Human leukocyte elastase and cathepsin G are specific inhibitors of C5a-dependent neutrophil enzyme release and chemotaxis

Circulating human neutrophils from patients with severe inflammatory disorders such as erysipelas and sepsis are specifically desensitized to complement factor C5a stimulation but not to stimulation with other stimuli like N-formyl-methionyl-leucyl-phenylalanine (FMLP), interleukin-8 (IL-8), leukotriene B4 (LTB4), or platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine). In this study, we raised the question whether factors released from polymorphonuclear leukocytes (PMNs) can specifically down-regulate C5a-dependent neutrophil functions. When neutrophils were preincubated with either neutrophil lysates or neutrophil degranulation supernatants, a complete inhibition of C5a-stimulated beta-glucuronidase release and chemotaxis could be observed, whereas FMLP-, IL-8-, LTB4- or PAF-dependent functions were not affected. Serine protease inhibitors like phenylmethylsulfonyl fluoride, antileukoprotease, or elafin abolished this effect. High-performance liquid chromatography of neutrophil degranulation supernatants revealed pronounced inhibition of C5a-dependent neutrophil functions in fractions exerting elastase or cathepsin G activity, but not in fractions exerting proteinase 3 activity. Using purified human leukocyte elastase (HLE), C5a responses like intracellular calcium influx, beta-glucuronidase release, and chemotaxis were also specifically inhibited. Our experiments show that the release of HLE or cathepsin G from neutrophils specifically down-regulates the responsiveness of neutrophils to C5a. Elastase and cathepsin G may therefore play an important role in the down-regulation of acute inflammation.

Antimicrobial psoriasin (S100A7) protects human skin from Escherichia coli infection

Human healthy skin is continuously exposed to bacteria, but is particularly resistant to the common gut bacterium Escherichia coli. We show here that keratinocytes secrete, as the main E. coli-killing compound, the S100 protein psoriasin in vitro and in vivo in a site-dependent way. In vivo treatment of human skin with antibodies to psoriasin inhibited its E. coli-killing properties. Psoriasin was induced in keratinocytes in vitro and in vivo by E. coli, indicating that its focal expression in skin may derive from local microbial induction. Zn(2+)-saturated psoriasin showed diminished antimicrobial activity, suggesting that Zn(2+) sequestration could be a possible antimicrobial mechanism. Thus, psoriasin may be key to the resistance of skin against E. coli.

Biologically active neutrophil chemokine pattern in tonsillitis

To gain an insight into the mechanisms of chronic and acute inflammation, the production of neutrophil chemokines in different types of tonsillitis - hyperplastic tonsillitis (HT), recurrent tonsillitis (RT) and peritonsillar abscesses (PA) - was investigated. The chemokines interleukin-8 (IL-8), growth-related oncogene-alpha (GRO-alpha), epithelial cell-derived neutrophil attractant-78 (ENA-78) and granulocyte chemotactic protein-2 (GCP-2) were detected and shown to have different biological activities. With respect to the biological properties of CXC chemokines, the biological activity of the chemokines was identified using a three-step high-performance liquid chromatography (HPLC) technique, a bioassay involving measurement of neutrophil chemotaxis in a single Boyden chamber in tissue of HT, RT and PA. Using reverse transcription-polymerase chain reaction (RT-PCR), the chemokine concentrations were determined in the different tonsillitis entities. The chemokine pattern was dominated in PA by IL-8 and GRO-alpha and in RT by GRO-alpha. Hyperplastic tonsils of patients without a history of infection generated about five times lower IL-8 than PA. A protein concentration of GCP-2 was induced in PA and RT, whereas ENA-78 remained the same in all entities. In conclusion, it would appear that IL-8 was up-regulated in acute inflammation, whereas GRO-alpha dominated in chronic inflammation. ENA-78 seems not to play a pivotal role in inflammatory processes in tonsils. GCP-2 may serve as a substitute chemokine in certain inflammatory conditions as its quantity of mRNA and protein was higher in RT and PA than in HT.

The primary role in biologic activity of the neutrophil chemokines IL-8 and GRO-alpha in cultured nasal epithelial cells

Primary nasal epithelial cells were investigated for their ability to synthesize and deliver neutrophil chemotactic factors (chemokines) following tumor necrosis factor-alpha (TNF-alpha) induction. The chemokines interleukin8 (IL-8), growth-related oncogene-alpha (GRO-alpha), epithelial cell-derived neutrophil attractant-78 (ENA-78), and granulocyte chemotactic protein-2 (GCP-2) have been detected and characterized and shown to have different potencies in the chemotaxis of neutrophils. Cultures of primary nasal epithelial cells were treated with TNF-alpha in concentrations of 20 and 200 ng/ml for 2, 8, 24, and 72 h. The chemokine protein concentrations in the supernatants of the incubations were determined by the ELISA technique. Chemokine mRNA expression in epithelial cells was also measured using the reverse transcriptase-polymerase chain reaction (RT-PCR). The biologic activity of the chemokines was identified using a three-step high-performance liquid chromatography (HPLC) technique, a bioassay involving measurement of neutrophil chemotaxis in a single Boyden chamber. Both the IL-8 and GRO-alpha proteins and their respective mRNA appear to be induced by TNF-alpha in epithelial cells. The chemotactic responsiveness of both GRO-alpha and IL-8 appears to predominate after 24 h incubation with TNF-alpha. The chemokines GCP-2 and ENA-78 were only weakly induced by TNF-alpha. The neutrophil chemokines IL-8 and GRO-alpha were synthesized in nasal epithelial cell culture induced by TNF-alpha in biologically active concentrations of 0.8 ng/ml and 1.42 ng/ml, respectively. It appears that both the IL-8 and GRO-alpha chemokines may contribute to neutrophil tissue migration in sinusitis, whereas GCP-2 and ENA-78 are of secondary importance to the chemotaxis of neutrophils in this condition.

Neutrophil chemokines in cultured nasal fibroblasts

BACKGROUND

To gain insight into the mechanisms responsible for tissue neutrophil immigration in sinusitis, primary nasal fibroblasts are analyzed for synthesizing and delivering neutrophil chemokines.

METHODS

Primary nasal fibroblast cell culture was treated with tumor necrosis factor (TNF)-alpha concentrations of 20 and 200 ng/ml for 2, 8, 24 and 72 h. Chemokine concentrations in supernatants were determined by enzyme-linked immunoassay (ELISA) and chemokine mRNA expression in fibroblasts was measured by reverse transcriptase polymerase chain reaction (RT-PCR). Biological chemotactic activity was identified by three-step high-performance liquid chromatography (HPLC) and by bioassay measuring neutrophil chemotaxis in a single Boyden chamber system.

RESULTS

Interleukin (IL)-8 and growth-related oncogene (GRO)-alpha were induced in nasal fibroblast culture by proinflammatory stimulus. After 24 h of stimulation neutrophil chemotactic activity only was detected for IL-8. Granulocyte chemotactic protein (GCP)-2 mRNA was already significantly up-regulated after 2 h of stimulation.

CONCLUSION

Induction of IL-8 protein dominates chemokine synthesis 24 and 72 h after stimulation, whereas induction of GCP-2 mRNA seems to have a role in the early phase after 2 h of exposition with TNF-alpha.

Identification of diacylated ureas as a novel family of fungus-specific leukocyte-activating pathogen-associated molecules

Polymorphonuclear leukocytes represent primary components of the host's innate immune defenses against fungal infection, suggesting involvement of fungal leukocyte attractants. We have found in various fungi, but not in bacteria or host cells, unstable lipid-like leukocyte chemoattractants, which also induced adherence and degranulation in human neutrophils. Purification from bakers' yeast and structural analyses by electrospray mass spectrometry, (1)H NMR spectroscopy, and chemical synthesis revealed these inflammatory mediators as diacylated ureas, a novel class of unstable lipoids. The N,N'-dipalmitoleyl urea appeared to be the most potent innate immune responses inducing compound eliciting half-maximum neutrophil chemotactic activity at 140 nm. The all-trans isomer, N,N'-dipalmitelaidyl urea, was found to be inactive with respect to stimulation of degranulation in neutrophils, which indicates a Delta(9) cis-double bond to be essential for bioactivity of these diacyl ureas. N,N'-Dipalmitoleyl urea elicited Ca(2+) mobilization in neutrophils, which was found to be pertussis toxin-sensitive and sensitive toward a carboxylmethyltransferase inhibitor, indicating that these diacyl ureas activate leukocytes via a putative Galpha(i)-protein-coupled receptor. Their isolation exclusively from fungi suggests that these lipoids are fungus-specific pathogen-associated molecules that may alert the human innate immunity system to the presence of a fungal infection.

The role of the Duffy antigen-related chemokine receptor in psoriasis vulgaris

Chemokines represent a family of potent biological mediators. Within the group of receptors mediating their effects, a promiscuous receptor has been found which is able to bind and inactivate diverse chemokines of both C-C and C-X-C families. It is co-localized with blood group antigens of the Duffy system on the same glycoprotein and expressed on red blood cells as well as post-capillary blood vessels. In the present study three aspects of Duffy pathophysiology were studied: firstly the amount of IL-8 and RANTES binding to red blood cells and its correlation to disease activity of psoriatic patients, secondly the distribution of Duffy phenotype among psoriatic patients and thirdly the expression of Duffy antigen in normal vs psoriatic skin. Red blood cells from psoriatic patients (n=50) were lysed by triton X (1%) and supernatants tested in IL-8- and RANTES sandwich-ELISA. Duffy phenotype of psoriatic patients (n=50) was assessed by typing red blood cells with specific antisera in indirect Coombs technique. For immunohistochemical detection in normal and psoriatic skin (n=10 respectively) a specific monoclonal antibody (Fy6) was used. Neither IL-8- nor RANTES-levels on red blood cells correlated to disease activity and distribution of Duffy phenotype in psoriatics was not significantly altered when compared to the normal population. Furthermore, Duffy antigen was expressed in a similar pattern in normal and psoriatic skin at all parts of vasculature, albeit much more abundantly in diseased skin. Altogether, chemokine binding to red blood cells seems of minor importance in psoriasis. However, Duffy antigen together with other binding mechanisms like proteoglycans may play a role at local level by binding locally produced chemokines. Thus biological effects of chemokines are both restricted and focussed to dermal tissue.

Characterization and functional analysis of granulocyte concentrates collected from donors after repeated G-CSF stimulation

BACKGROUND

Neutropenic patients often develop bacterial or fungal infections not responding to broad-spectrum antibacterial or antifungal agents. Clinical efforts were made with transfusion of granulocyte concentrates; however, functions of granulocytes after multiple G-CSF stimulations and after apheresis are not yet investigated and described sufficiently.

STUDY DESIGN AND METHODS

The aim of this study was to characterize functional and immunologic variables of granulocytes in blood samples drawn from donors before and after each stimulation episode with G-CSF, in the resulting granulocyte concentrates and in the patients 8 hours after transfusion.

RESULTS

Chemotaxis was not influenced, neither by G-CSF application nor by apheresis. Multiple G-CSF stimulations enhanced oxidative burst and phagocytosis of Escherichia coli in donor granulocytes. These values returned to basal levels in granulocyte concentrates. Expression of granulocytic surface antigens was downregulated after application of G-CSF but returned to normal and in part enhanced values in concentrates. A clinically relevant increase of proinflammatory cytokines could not be detected. Leukotriene B4 production was reduced after the fourth G-CSF stimulation in the donor blood and enhanced in the granulocyte concentrate after apheresis. Results in recipients indicate that changes of granulocyte function noted in concentrates were only transient.

CONCLUSION

Stimulation of healthy donors with repeated G-CSF injections and subsequent granulocyte apheresis does not dramatically change decisive functions of granulocytes.

Development of a new method of analysing chemotactic deactivation of human neutrophil granulocytes

Measurement of chemotactic migration of human neutrophil granulocytes (PMN) induced by chemotaxins serves as a simple and reliable method for assessing the expression of chemotaxin receptors. Incubation of PMN with a certain chemotaxin leads to a diminished chemotactic migration towards this chemotaxin. This is called chemotactic deactivation. We developed a new deactivation chamber to determine chemotaxis and chemotactic deactivation of human PMN. This novel chamber is a modification of the commercially available acrylic 48-well microchemotaxis chamber consisting of an upper block with wells drilled all the way through the block and a blind-well lower block. Both blocks are separated by a polycarbonate membrane. PMN from the wells in the upper block migrate through the pores of the membrane into the wells of the lower block containing the chemoattractants. Migrated PMN on the lower side of the PC membrane were quantified after staining by measuring specific light absorbance. The chemotactic activity is quantified as a ratio of stimulated migration and random migration (chemotactic index=CI). For our novel chamber, only the upper blocks of this commercial chamber were connected like a sandwich, including a polyvinylpyrrolidone-free polycarbonate membrane with a pore size of 3 microm. The wells in the upper compartment were filled with 5 x 10(4) PMN and deactivating chemotaxin. The lower block was then filled with the chemotactic stimulus and the chamber was then incubated in humidified air with 5% CO2 atmosphere at 37 degrees C. The influence of cell concentration, incubation time, chemotactic factor concentration, pore size and alkaline treatment of polycarbonate membranes on migrational activity of PMN have been investigated. The technique was rigorously standardized in order to optimize the assay conditions. The method is relatively simple, sensitive and fast. The determination of chemotaxis and deactivation are performed in the same chamber, thus avoiding cell loss due to nonspecific adherence in other incubation tubes. The chamber can be used to characterize the chemotactic activity of chemoattractants of unknown structure via known and unknown receptors. This new chamber can be very helpful in detecting unknown chemotactic stimuli, which are not detectable by, for example, antibodies.

Isolation and purification of chemokines from natural sources

Chemokines (e.g., IL-8) were originally identified as chemotactic proteins obtained from various different natural sources. Today, using the genome walking strategy an ever-increasing number of novel genes encoding chemokines have been discovered that were expressed in bacteria or eukaryotic cells and subsequently tested for biological activity. Usually biological significance of the considered chemokine is extrapolated from these data. The increasing evidence, however, that post-translational modification of chemokines can dramatically affect its biological activity makes it necessary to identify the naturally occurring chemokines in order to identify its biological function. Furthermore, with the isolation of natural chemokines, evidence is provided that transcription of chemokine genes is really followed by translation into a bioactive molecule. Purification of chemokines from natural sources requires special strategies: The bioassay or immunoassay should allow screening of high-performance liquid chromatography fractions and detection of the required chemokine at low concentration. Parameters that affect the detection of bioactivity and immunoreactivity (giving either false positive or false negative results) should be carefully considered. In this article methods for molecular characterization of chemokines from both cell culture supernatants and human tissue (lesional inflammatory skin scales) will be described.

Amino-terminally modified RANTES analogues demonstrate differential effects on RANTES receptors

Modification of the amino terminus of regulated on activated normal T-cell expressed (RANTES) has been shown to have a significant effect on biological activity and produces proteins with antagonist properties. Two amino-terminally modified RANTES proteins, Met-RANTES and aminooxypentane-RANTES (AOP-RANTES), exhibit differential inhibitory properties on both monocyte and eosinophil chemotaxis. We have investigated their binding properties as well as their ability to activate the RANTES receptors CCR1, CCR3, and CCR5 in cell lines overexpressing these receptors. We show that Met-RANTES has weak activity in eliciting a calcium response in Chinese hamster ovary cells expressing CCR1, CCR3, and CCR5, whereas AOP-RANTES has full agonist activity on CCR5 but is less effective on CCR3 and CCR1. Their ability to induce chemotaxis of the murine pre-B lymphoma cell line, L1.2, transfected with the same receptors, consolidates these results. Monocytes have detectable mRNA for CCR1, CCR2, CCR3, CCR4, and CCR5, and they respond to the ligands for these receptors in chemotaxis but not always in calcium mobilization. AOP-RANTES does not induce calcium mobilization in circulating monocytes but is able to do so as these cells acquire the macrophage phenotype, which coincides with a concomitant up-regulation of CCR5. We have also tested the ability of both modified proteins to induce chemotaxis of freshly isolated monocytes and eosinophils. Cells from most donors do not respond, but occasionally cells from a particular donor do respond, particularly to AOP-RANTES. We therefore hypothesize that the occasional activity of AOP-RANTES to induce leukocyte chemotaxis is due to donor to donor variation of receptor expression.

The role of chemokines in cutaneous allergic inflammation

Eosinophils are the major effector cells that kill helminthic parasites and are - for unknown reasons present in the dermal part of atopic skin. This review summarizes our knowledge on the chemotactic factors involved in eosinophil tissue recruitment, focusing on the role of eosinophil-chemotactic chemokines. It is the current view that the chemokines RANTES and eotaxin represent the most important eosinophil-attracting chemokines. The inducibility of eotaxin in dermal fibroblasts only upon stimulation with Th2-cytokines IL-4 and IL-13 may explain why eosinophils appear only in the dermis and why the presence of Th2-cytokines is always linked with tissue eosinophilia.

The Biologic Role of Interleukin-8: Functional Analysis and Expression of CXCR1 and CXCR2 on Human Eosinophils

Chemokines play an important role in attracting granulocytes into sites of inflammation. Two chemokine subfamilies differ in their biologic activity for different granulocyte subsets. Whereas CXC chemokines such as interleukin-8 (IL-8) activate predominantly neutrophils, CC chemokines such as RANTES and eotaxin activate predominantly eosinophils. However, controversial results have been published in the past regarding the biologic role of IL-8 in eosinophil activation, particularly in allergic diseases. In this study, we investigated the functional evidence and expression of both IL-8 receptors, CXCR1 and CXCR2, on highly purified human eosinophils. In the first set of experiments, a chemotaxis assay was performed showing that IL-8 did not induce chemotaxis of eosinophils. In addition, and in contrast to neutrophils and lymphocytes, IL-8 did not induce a rapid and transient release of cytosolic free Ca2+([Ca2+]i) in eosinophils, even after preincubation with TH1- and TH2-like cytokines. To investigate whether neutrophil contamination might be responsible for the reported IL-8 effects on eosinophils, neutrophils were added to highly purified eosinophils from the same donor in different concentrations. Interestingly, as little as 5% of neutrophil contamination was sufficient to induce an increase of [Ca2+]iafter stimulation with IL-8. Flow cytometry experiments with monoclonal antibodies against both IL-8 receptors demonstrated no expression of CXCR1 and CXCR2 on eosinophils before or after cytokine activation. Reverse transcriptase-polymerase chain reaction experiments showed that eosinophils, in contrast to neutrophils and lymphocytes, did not express mRNA for CXCR1 and CXCR2. In summary, this study clearly demonstrates that CXCR1 and CXCR2 are not expressed on human eosinophils, even after priming with different bioactive cytokines. Because the CXC chemokine IL-8 did not induce in vitro effects on human eosinophils, IL-8 may also not contribute in vivo to the influx of eosinophil granulocytes into sites of allergic inflammation. Our results suggest that CC chemokines such as eotaxin, eotaxin-2, and MCP-4 are predominant for the activation of eosinophils.

The Biologic Role of Interleukin-8: Functional Analysis and Expression of CXCR1 and CXCR2 on Human Eosinophils

Chemokines play an important role in attracting granulocytes into sites of inflammation. Two chemokine subfamilies differ in their biologic activity for different granulocyte subsets. Whereas CXC chemokines such as interleukin-8 (IL-8) activate predominantly neutrophils, CC chemokines such as RANTES and eotaxin activate predominantly eosinophils. However, controversial results have been published in the past regarding the biologic role of IL-8 in eosinophil activation, particularly in allergic diseases. In this study, we investigated the functional evidence and expression of both IL-8 receptors, CXCR1 and CXCR2, on highly purified human eosinophils. In the first set of experiments, a chemotaxis assay was performed showing that IL-8 did not induce chemotaxis of eosinophils. In addition, and in contrast to neutrophils and lymphocytes, IL-8 did not induce a rapid and transient release of cytosolic free Ca2+([Ca2+]i) in eosinophils, even after preincubation with TH1- and TH2-like cytokines. To investigate whether neutrophil contamination might be responsible for the reported IL-8 effects on eosinophils, neutrophils were added to highly purified eosinophils from the same donor in different concentrations. Interestingly, as little as 5% of neutrophil contamination was sufficient to induce an increase of [Ca2+]iafter stimulation with IL-8. Flow cytometry experiments with monoclonal antibodies against both IL-8 receptors demonstrated no expression of CXCR1 and CXCR2 on eosinophils before or after cytokine activation. Reverse transcriptase-polymerase chain reaction experiments showed that eosinophils, in contrast to neutrophils and lymphocytes, did not express mRNA for CXCR1 and CXCR2. In summary, this study clearly demonstrates that CXCR1 and CXCR2 are not expressed on human eosinophils, even after priming with different bioactive cytokines. Because the CXC chemokine IL-8 did not induce in vitro effects on human eosinophils, IL-8 may also not contribute in vivo to the influx of eosinophil granulocytes into sites of allergic inflammation. Our results suggest that CC chemokines such as eotaxin, eotaxin-2, and MCP-4 are predominant for the activation of eosinophils.