Biphasic expression of stromal cell-derived factor-1 during human wound healing.

BACKGROUND: Chemokines tightly regulate the spatial and temporal infiltration of invading leucocyte subsets during wound healing. Stromal cell-derived factor-1 (SDF-1/CXCL12) is a homeostatic chemokine with multiple functions; its role during cutaneous wound healing, however, needs to be explored. OBJECTIVES: To elucidate expression of the multifunctional CXC chemokine SDF-1/CXCL12 during human wound healing. METHODS: Skin biopsies were obtained from 14 volunteers between 1 and 21 days after incisional wounding and processed for in situ hybridization and immunohistochemistry. RESULTS: We analysed the spatial and temporal distribution of SDF-1/CXCL12 after artificial wounding and detected a complete downregulation at both the mRNA and the protein level within the fibrous stroma that replaces the initial wound defect. However, increased levels of SDF-1/CXCL12 were observed at the wound margins. Focusing on mediators regulating SDF-1/CXCL12 expression in vitro we realized that both tumour necrosis factor-alpha and interferon-gamma downregulated its expression in human dermal microvascular endothelial cells and fibroblasts. CONCLUSIONS: Our data suggest that SDF-1/CXCL12 is tightly regulated during wound repair. Increased expression at the wound margin may contribute to the accumulation of endothelial progenitor cells, thus accelerating neovascularization.

Elevated serum levels of calcium-binding S100 proteins A8 and A9 reflect disease activity and abnormal differentiation of keratinocytes in psoriasis.

BACKGROUND: The expression of calcium-binding S100 molecules organized within the epidermal differentiation complex on chromosome 1q21 is disturbed in hyperproliferative skin diseases such as psoriasis. OBJECTIVES: We studied whether serum levels of S100 proteins A8 (S100A8) and A9 (S100A9) are elevated in psoriasis, correlated their amounts with disease activity and identified potential cellular sources. METHODS: Serum obtained from psoriasis patients or from healthy individuals was studied for S100A8 and S100A9 levels by enzyme-linked immunosorbent assay. Data were correlated to disease activity as reflected by the Psoriasis Area and Severity Index (PASI). Cellular sources of S100A8 and S100A9 were identified by in situ hybridization and immunohistochemistry of lesional psoriatic and nonlesional, nonpsoriatic skin. RESULTS: A significant increase of S100A8/S100A9 serum levels was found in patients with psoriasis compared with healthy controls. Grading the patients into two groups of severity, individuals with a PASI of <15 showed serum levels of 705+/-120 ng mL-1 (mean+/-SEM, n=18), those with a PASI of >or=15 showed levels of 1315+/-150 ng mL-1 (n=32) while controls presented with 365+/-50 ng mL-1. Performing in situ hybridization of lesional psoriatic skin we detected a dramatic induction of both S100A8 and S100A9 mRNA and protein primarily in the suprabasal layers of the epidermis while expression was negligible in nonlesional, nonpsoriatic interfollicular epidermis. CONCLUSIONS: Our data demonstrate that hyperproliferation and abnormal differentiation of psoriatic skin is associated with a massive upregulation and secretion of S100A8 and S100A9, suggesting not only a prominent role of these molecules during intracellular calcium-dependent signalling but also implying distinct extracellular functions.

Treatment of recalcitrant pustular psoriasis with infliximab: effective reduction of chemokine expression.

Tumour necrosis factor (TNF)-alpha is thought to play a major role in the pathophysiology of psoriasis. Good clinical responses of psoriasis to anti-TNF-alpha-based therapies have recently been demonstrated. We studied the effect of infliximab, a monoclonal antibody against TNF-alpha, on chemokine expression in pustular psoriasis. A 61-year-old man with a 2-year history of severe pustular psoriasis of von Zumbusch type who did not respond to conventional therapies responded rapidly to treatment with infliximab. The clinical response was reflected by an immediate and effective reduction of the neutrophil-attractant chemokines interleukin (IL)-8 and growth-related oncogene (Gro)-alpha as well as of monocyte chemoattractant protein (MCP)-1, as determined by mRNA in situ hybridization of lesional skin. No expression before or after treatment was seen for monokine induced by interferon (IFN)-gamma (MIG) and IFN-inducible protein (IP)-10. Thus, in pustular psoriasis the chemokine expression pattern is dominated by neutrophil-attractant chemokines and MCP-1 while, in contrast to plaque psoriasis, IFN-gamma-inducible lymphocyte-attractant chemokines such as IP-10 and MIG are not abundant. We conclude that anti-TNF-alpha treatment with infliximab is an effective therapy in severe pustular psoriasis which is reflected by downregulation of disease-promoting chemokines such as IL-8, Gro-alpha and MCP-1.

Differential and sequential expression of multiple chemokines during elicitation of allergic contact hypersensitivity.

Regulation of chemokine-mediated leukocyte migration within inflammatory tissues is a complex event that cannot be mimicked and analyzed in vitro. We therefore investigated the role of macrophage- and T-lymphocyte-specific chemoattractants involved in the positioning of immune effector cells during the elicitation phase of contact hypersensitivity, a prototype of a T-lymphocyte-mediated immune reaction. Serial sections of skin biopsies obtained from sensitized individuals at distinct time intervals after epicutaneous application of allergens were hybridized with anti-sense probes of a large panel of chemokines or immunohistologically labeled with leukocyte-specific antibodies. Multifocal expression of monocyte chemoattractant protein-1 (MCP-1) was already detected after 6 hours in basal keratinocytes clearly preceding the infiltration of monocytes and T cells. Increasing basal expression of MCP-1 and, in addition, of regulated upon activation, normal T-cell expressed and secreted (RANTES) after 12 hours was accompanied by dermal expression of MCP-1, macrophage-derived chemoattractant (MDC), and RANTES and paralleled by infiltration of mononuclear cells into dermis and epidermis. Expression of the T-lymphocyte-specific chemokines IP-10 and MIG in epidermis and dermis and of MDC, pulmonary and activation-regulated chemokine (PARC), and thymus and activation-regulated chemokine (TARC) exclusively in the dermis started after 12 hours reaching maximum levels at 72 hours and was associated with infiltration of T cells into the epidermal compartment. Our data provide evidence that migrating effector cells encounter multiple chemoattractant signals in a complex spatial and temporal pattern. In particular, keratinocytes contribute to the vigorous immigration by sequential expression of MCP-1, RANTES, and interferon-inducible protein-10 (IP-10) monokine induced by gamma interferon (MIG), indicating that chemokine-mediated nonimmunological mechanisms precede and corroborate antigen-specific mechanisms during elicitation of contact hypersensitivity.

CXC chemokines Gro(alpha)/IL-8 and IP-10/MIG in Helicobacter pylori gastritis.

Infection with Helicobacter pylori causes chronic active gastritis, which is characterized by neutrophils infiltrating the gastric epithelial layer and the underlying lamina propria as well as by T, B lymphocytes and macrophages accumulating in the lamina propria. In this study, the chemokine profile responsible for the recruitment of these inflammatory cells is investigated. Using both RNA/RNA in situ hybridization and immunohistochemistry, the expression of the neutrophil and/or lymphocyte-attractant CXC chemokines growth-related oncogene alpha (Gro(alpha)), IL-8, interferon-gamma (IFN-gamma)-inducible protein-10 (IP-10), monokine induced by IFN-gamma (MIG) and the CC chemokines macrophage inflammatory protein-1alpha (MIP-1alpha), -1beta, regulated on activation normal T cell expressed and secreted (RANTES) and monocyte chemoattractant protein-1 (MCP-1) is studied and microanatomically localized in the gastric mucosa. Macrophages in the lamina propria at sites with neutrophil infiltration and gastric epithelium infiltrated by neutrophils highly expressed the neutrophil-attractant chemokines Gro(alpha) and IL-8. Additionally, Gro(alpha) and IL-8 were expressed by neutrophils themselves localized within gastric epithelium, in the foveolar lumen and in the cellular debris overlying mucosal erosion. IP-10 and to a lower extent MIG, both selectively chemotactic for inflammatory T cells, were expressed by endothelial cells of gastric mucosal vessels and by mononuclear cells at sites with T cell infiltration. Expression of all other CC chemokines tested was significantly lower. These in vivo data indicate that a set of predominantly CXC chemokines modulates the inflammation in H. pylori gastritis. Gro(alpha) and IL-8 may play an important role in neutrophil trafficking from the mucosal vessel into the gastric epithelium, whereas IP-10 and MIG contribute to the recruitment of inflammatory T cells into the mucosa.

[Role of chemokines in human skin wound healing]. / Die Rolle der Chemokine bei der Wundheilung der menschlichen Haut.

The healing process of skin wounds is regulated by growth factors which stimulate proliferation of resident cells and their synthesis of extra cellular matrixcomponents. Different leukocyte subtypes (neutrophils, macrophages, lymphocytes and mast cells) participate in wound healing not only as immunological effector cells but also as an important source of inflammatory and growth promoting cytokines. Rapid recruitment of leukocytes and their positioning is tightly regulated by a temporally and spatially changing set of chemokines. Whereas expression of IL-8 and GRO (growth related oncogene) direct early neutrophil recruitment, migration of macrophages is stimulated by MCP-1 (monocyte chemoattractant protein-1) and later, lymphocytes are attracted by IP-10 (gamma-interferon inducible protein-10) and Mig (monokine induced by interferon-gamma). Since chemokines as IL-8 and GRO also stimulate angiogenesis and keratinocyte proliferation, they integrate the inflammatory events with the reparative processes and are potential candidates in the search of wound healing agents.

Mig, GRO alpha and RANTES messenger RNA expression in lining layer, infiltrates and different leucocyte populations of synovial tissue from patients with rheumatoid arthritis, psoriatic arthritis and osteoarthritis.

To investigate lymphocyte and monocyte recruitment-specific chemokine expression in synovial tissues from patients with rheumatoid arthritis (RA), psoriatic arthritis (PA) and osteoarthritis (OA), synovial membranes and cytocentrifuge preparations of 7 RA, 8 PA and 10 OA patients were examined by in situ hybridisation with antisense probes of Mig, GRO alpha and RANTES and by immunohistochemistry. Patients' local disease activity (swelling and tenderness) in order to was graded and histological evaluation was performed compare these data with their chemokine expression profiles. Mig and RANTES hybridisation signals were detected in the synovial lining layer and in cellular infiltrates, whereas GRO alpha expression was localised exclusively in the lining layer of PA and RA. Cytological analysis revealed Mig and GRO alpha mRNA mainly in monocytic cells expressing KIM6, while RANTES mRNA was demonstrated predominantly in lymphocytic cells expressing CD3. In OA synovial membranes, significantly fewer hybridisation signals were present than in RA and PA synovial membranes. Patients with PA and RA had mild to severe local disease activity, whereas OA patients showed only mild disease activity. Histologically, PA and RA inflammatory scores ranged from 1 to 5, while OA synovium was consistently graded 1. Therefore, we conclude that the differential expression of Mig, GRO alpha and RANTES in resident and in inflammatory cells has an important role in regulating leucocyte traffic in inflammatory arthropathies. The diverse leucocyte specificity of Mig, GRO alpha and RANTES may thus regulate the recruitment of different leucocyte populations, as detected in PA and RA. Therefore, the pattern of cellular infiltration in human synovitis and the corresponding clinical signs of inflammation basically reflect the localisation and expression intensity of chemokines, which may be an important target for future disease modulation.

Mast cell involvement in normal human skin wound healing: expression of monocyte chemoattractant protein-1 is correlated with recruitment of mast cells which synthesize interleukin-4 in vivo.

Mast cells (MCs) are known as key cells of immediate type hypersensitivity reactions. It has recently been shown that MCs regulate fibroblast proliferation by heterotypic cell-cell contact and secretion of interleukin-4 (IL-4) in vitro. It was therefore hypothesized that MCs may contribute to wound repair in vivo. Using immunohistology and in situ hybridization, the time course of mast cell recruitment and the expression of MC-attractant chemokines were analysed in a human skin wound-healing model, and the production of IL-4 by MCs in vivo was investigated. The data obtained indicate that the five-fold increase of the tryptase+ MCs at the fibrotic border of the wound within the first 10 days is the result of increased recruitment/survival of MCs or MC precursors, but not of increased local proliferation. Recruitment of MCs is paralleled by the expression of monocyte chemoattractant protein-1 (MCP-1), but not by other chemokines such as RANTES (regulated on activation, normal T cell expressed and secreted) and/or MIP (macrophage inflammatory protein)-1alpha/beta. Notably, 60-70% of MCs exhibited strong and selective IL-4 immunoreactivity, whereas other resident and passenger cells were rather quiescent. The data suggest that MC contribute significantly to the cytokine network of wound repair via MC-derived IL-4 and stimulation of fibroblast proliferation.

Anoxia-induced up-regulation of interleukin-8 in human malignant melanoma. A potential mechanism for high tumor aggressiveness.

Besides its proinflammatory properties, interleukin-8 (IL-8) has been suggested as an important promoter for melanoma growth. To study the role of IL-8 in melanoma biology, we determined the in vivo expression of IL-8 mRNA by in situ hybridization in primary melanoma lesions and metastases. High levels of melanoma cell-associated IL-8-specific transcripts were exclusively detected in close vicinity of necrotic/hypoxic areas of melanoma metastases, whereas both in primary melanomas and in non-necrotic metastases IL-8 expression was low or absent. To analyze further the up-regulation of IL-8 mRNA expression in necrotic/hypoxic tumor areas, human melanoma cell lines of different aggressiveness exposed to severe hypoxic stress (anoxia) were used as an in vitro model. Anoxia induced IL-8 mRNA and protein expression in the highly aggressive/metastatic cell lines MV3 and BLM but not in the low aggressive cell lines IF6 and 530. As shown by IL-8 promoter-dependent reporter gene analysis and mRNA stability assays, elevated mRNA levels in melanoma cells were due to both enhanced transcriptional activation and enhanced IL-8 mRNA stability. Interestingly, transcriptional activation was abolished by mutations in the AP-1 and the NF-kappaB-like binding motifs, indicating that both sites are critical for IL-8 induction. Concomitantly, anoxia induced an enhanced binding activity of AP-1 and NF-kappaB transcription factors only in the highly aggressive cells. From our in vitro and in vivo data we suggest that anoxia-induced regulation of IL-8 might be a characteristic feature of aggressive tumor cells, thus indicating that IL-8 might play a critical role for tumor progression in human malignant melanoma.

Hypoxia-induced up-regulation of angiogenin in human malignant melanoma.

Angiogenesis is essential for tumor progression and metastasis, however, the angiogenesis regulators that are biologically relevant for human melanoma are still unknown. In this study, we analyzed the expression of the potent angiogenic factor angiogenin (ANG) in human melanoma in vitro and in vivo. Four different human melanoma cell lines and two normal melanocytes were kept either under normoxic or hypoxic conditions. After 24 h of hypoxic culture conditions, ANG was up-regulated in the melanoma cell lines but not in normal melanocytes. Induction levels correlated with the metastatic potential of the cell lines. These data were confirmed by Northern blot analysis. In contrast, induction of vascular endothelial growth factor by hypoxia was equally strong in the examined highly aggressive melanoma cell lines and in one nonaggressive cell line. Other angiogenic factors tested as well as the melanoma growth stimulatory activity (Gro-alpha) showed no up-regulation. Thus, in the present study, hypoxia-induced up-regulation in melanoma cells was only observed for ANG and vascular endothelial growth factor. Immunohistochemical studies showed that 8 of 10 melanomas and all 15 metastases were positive for ANG, particularly in the vicinity of small vessels, whereas all benign nevi were negative. Reverse transcription-PCR detected only weak ANG mRNA in nevi but strong signals in primary melanomas and metastases. In conclusion, we demonstrate for the first time enhanced expression of ANG in highly metastatic cell lines as well as in melanomas and metastases in vivo, suggesting that ANG expression is associated with the metastatic potential.

Strong expression of the lymphoattractant C-X-C chemokine Mig is associated with heavy infiltration of T cells in human malignant melanoma.

Human malignant melanoma (MM) is a highly aggressive tumour which is particularly prone to specific local immune responses. To determine the microanatomical location and the species of chemokines possibly involved in the intricate control of cell migration and positioning of immune effector cells in primary and metastatic MM lesions, the expression of those chemokines with lymphocyte and/or macrophage chemoattractant properties was analysed by in situ hybridization. GROalpha (growth-related oncogene) and IL-8 (interleukin 8) were expressed at low levels by single melanoma cells, adjacent keratinocytes, and infiltrating leukocytes. In contrast, the lymphocyte-specific chemokine Mig (monokine induced by interferon-gamma) was strongly expressed by mononuclear cells (mainly macrophages) infiltrating the tumour margin in primary MM lesions, whereas expression was less intense in MM metastasis. IP-10 (interferon-gamma inducible protein 10) was expressed in the same loci at lower intensity. Marked infiltration of T cells was exclusively detected in those areas which exhibited strong Mig expression, whereas areas in the vicinity of tumour cells devoid of Mig expression were not infiltrated. In contrast to Mig, expression of MCP-1 (macrophage chemotactic protein-1) was weaker and mainly detected in lesional basal keratinocytes, occasionally at sites of macrophage infiltration, as well as in single melanoma cells. MIP-1alpha (macrophage inflammatory protein 1alpha) showed similar, albeit weaker expression compared with MCP-1. Other chemokines relevant for the recruitment of monocytes and lymphocytes, such as RANTES (regulated on activation, normal T cells expressed and secreted) and MIP-1beta, were barely detectable. In summary, the chemokine expression profiles support the notion that particularly in heavily infiltrated primary MM lesions, Mig and to a lesser extent IP-10 are important mediators of an IFN-gamma-dependent pathway. Due to their lymphoattractant properties and the known inhibitory effects on the tumour vasculature, both chemokines may be critical for the control of local melanoma tumour growth.

MIG is a dominant lymphocyte-attractant chemokine in lichen planus lesions.

Dense accumulation of mononuclear cells (lymphocytes >> macrophages) in the dermal-epidermal interface and a T cell-mediated cytotoxic reaction against basal keratinocytes are hallmarks of lichen planus lesions. In this study, we focused on the chemotactic signals responsible for the selective recruitment of these cells. Using in situ hybridization and immunohistochemistry, the expression and localization of the lymphocyte-and/or monocyte/macrophage-attractant CC chemokines macrophage chemoattractant protein-1 (MCP-1), regulated on activation, normal T cell expressed, and secreted (RANTES), macrophage inflammatory protein-1alpha and -1alpha (MIP-1alpha/beta), I-309 and the CXC chemokines monokine induced by interferon-gamma (MIG), interferon-gamma-inducible protein-10 (IP-10), interleukin-8 (IL-8), epithelial-derived neutrophil attractant-78, and growth-related oncogene-alpha were investigated. Strong mRNA expression of MIG, IP-10, and MCP-1 and moderate mRNA expression of RANTES and MIP-1alpha were detected exclusively within foci characterized by strong infiltration with CD3+ lymphocytes (CD4+ cells > CD8+ cells) and CD68+ macrophages. All other chemokines investigated were minimally expressed or absent. With more than 11% of total cells strongly expressing MIG transcripts, this selectively lymphotactic chemokine was by far the dominant chemokine and thus may significantly contribute to the inflammatory reaction in lichen planus lesions. According to the mRNA expression profiles, MIG, IP-10, and MCP-1 were expressed by both basal keratinocytes above and mononuclear cells within the inflammatory foci. Our findings indicate that a set of chemokines composed of IP-10, MCP-1, RANTES, MIP-1alpha, and especially MIG contributes to the cytokine network and preferential trafficking of mononuclear cells to the interface region of lichen planus lesions.

Chemokines IL-8, GROalpha, MCP-1, IP-10, and Mig are sequentially and differentially expressed during phase-specific infiltration of leukocyte subsets in human wound healing.

Healing of cutaneous wounds requires a complex integrated network of repair mechanisms, including the action of newly recruited leukocytes. Using a skin repair model in adult humans, we investigated the role chemokines play in sequential infiltration of leukocyte subsets during wound healing. At day 1 after injury, the C-X-C chemokines IL-8 and growth-related oncogene alpha are maximally expressed in the superficial wound bed and are spatially and temporally associated with neutrophil infiltration. IL-8 and growth-related oncogene alpha profiles also correlate with keratinocyte migration and subsequently subside after wound closure at day 4. Macrophage infiltration reaches the highest levels at day 2 and is paralleled by monocyte chemoattractant protein-1 mRNA expression in both the basal layer of the proliferative epidermis at the wound margins and mononuclear cells in the wound area. Other monocyte-attracting chemokines such as monocyte chemoattractant protein-3, macrophage inflammatory protein-1alpha and -1beta, RANTES, and 1309 are undetectable. At day 4, perivascular focal lymphocyte accumulation correlates with strong focal expression of the C-X-C chemokines Mig and IP-10. Our results suggest that a dynamic set of chemokines contributes to the spatially and temporally different infiltration of leukocyte subsets and thus integrates the inflammatory and reparative processes during wound repair.

Isolation and recombinant expression of an MHV-JHM neutralising monoclonal antibody.

The monoclonal antibody A1 (mab A1) efficiently neutralises the infection of susceptible cells by the murine hepatitis virus MHV-JHM in vitro and in vivo (Wege et al., 1984). The variable regions of mab A1 were amplified from mRNA of the respective hybridoma cell line by RT-PCR and integrated into different eukaryotic expression vectors. The biological function of the recombinant antibody constructs was verified by virus neutralisation assays. Whereas a complete recombinant antibody (mab A1rec.) expressed in transfected murine myeloma cells inhibited the MHV-JHM infection as well as the parental antibody, a single-chain Fv derived from mab A1 did not show any neutralising activity.

The C-X-C chemokine Mig is highly expressed in the papillae of psoriatic lesions.

A prominent feature within the histopathological changes of psoriatic lesions is the particular spatial distribution of neutrophils, macrophages, and T-cell which are considered to participate in the pathogenesis of psoriasis. In this study, an attempt has been made to examine the microanatomical localization and magnitude of expression of the T-cell-attractant and -stimulating C-X-C and C-C chemokines Mig, interferon-inducible protein-10 (IP-10), macrophage inflammatory protein-1 alpha and 1 beta (MIP-a alpha and 1 beta), and regulated on activation, normal T-cell expressed and secreted (RANTES). Employing in situ hybridization, Mig message was strongly and selectively expressed in the upper lesional dermis with pronounced clustering in the tips of the papillae, whereas expression in normal or uninvolved skin was quiescent. In contrast, message for all the other chemokines investigated was much weaker or lacking. Expression of Mig transcripts in cell clusters of the papillae was paralleled by Mig immunoreactivity on endothelial and mononuclear cells. The expression profile, with high levels of Migs virtually limited to those lesional papillae with a pronounced infiltration of mononuclear leukocytes, strongly suggests that Mig is produced by a local population of highly activated macrophages and dermal microvascular endothelial cells. Considering the T-cell-attracting and -stimulating capacity of Mig and the importance of T-cells in the pathogenesis of psoriasis, this study indicates that this novel C-X-C chemokine plays an important role as a mediator of T-cell recruitment and activation in the papillae and thus contributes significantly to the cytokine network of inflammation in psoriasis.

Interleukin-13 selectively induces monocyte chemoattractant protein-1 synthesis and secretion by human endothelial cells. Involvement of IL-4R alpha and Stat6 phosphorylation.

Chemokines secreted by endothelium have been demonstrated to promote leucocyte recruitment to sites of inflammation. In the present study we investigated the effect of the T lymphocyte-secreted cytokine interleukin (IL)-13 on endothelial expression of chemokines. Employing in situ hybridization and enzyme-linked immunosorbent assay (ELISA) techniques we demonstrate that IL-13, which shares many of its activities with IL-4, selectively induces expression of the C-C chemokine monocyte chemoattractant protein (MCP)-1 in human umbilical vein endothelial cells (HUVEC). However, it fails to up-regulate other C-C and C-X-C chemokines potentially inducible in endothelium such as RANTES (regulated on activation, normal T expressed and secreted), gro-alpha, or IL-8. IL-13 dose-dependently induces monocyte chemotactic activity by HUVEC which can be efficiently blocked by neutralizing antisera against MCP-1. In contrast to the synergistic effect of IL-13 and tumour necrosis factor-alpha (TNF-alpha) on endothelial vascular cell adhesion molecule-1 (VCAM-1) surface expression, TNF-alpha-induced secretion of MCP-1 is not augmented by IL-13. Studying the signalling pathway activated by IL-13 it is demonstrated that a neutralizing monoclonal antibody (mAb) to the 140,000 MW component of the IL-4 receptor (IL-4R alpha) inhibits the effect of IL-13. Immunoprecipitation studies reveal that endothelial IL-4R alpha is rapidly tyrosine phosphorylated upon treatment with IL-13 and IL-4. We furthermore show that both cytokines activate the signal transducer and activator of transcription (Stat) protein-6 in endothelial cells. Our data suggest that IL-13 partly utilizes components of the IL-4 receptor signalling pathway for induction of endothelial MCP-1 expression to facilitate recruitment of blood leucocytes.

The chemokine repertoire of human dermal microvascular endothelial cells and its regulation by inflammatory cytokines.

Activation of endothelium is a critical event during the initiation of inflammatory processes and is associated with the induction of cell adhesion molecules and cytokines. The latter include chemotactically active cytokines (chemokines) that promote leukocyte diapedesis from the circulation to sites of evolving inflammation. In this study we evaluated the chemokine repertoire of human endothelial cells derived from the skin (HDMECs) and regulation of these chemokines by cytokines. HDMECs and an immortalized human dermal microvascular endothelial cell line, HMEC-1, were investigated for the expression of C-X-C and C-C chemokines at mRNA and protein levels. Upon stimulation with interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), both HDMECs and HMEC-1 expressed high levels of IL-8, GRO, and monocyte chemoattractant protein-1 (MCP-1). RANTES was only weakly induced; however, concomitant treatment with TNF-alpha and interferon-gamma (IFN-gamma) led to upregulation of RANTES, indicating a synergy between these two cytokines. The C-X-C chemokine IFN-inducible protein-10 was upregulated by IFN-gamma but not by other cytokines studied. Macrophage inflammatory protein-1alpha and beta, 1-309, and ENA-78 could not be induced. The chemokine repertoires of HDMECs and HMEC-1 were compared to those of human umbilical vein endothelium and found to be rather similar with the important exception that IFN-gamma and IL-4 up-regulated MCP-1 only in macrovascular endothelium. Our data indicate that HDMECs contribute to the dermal cytokine network by selective production of MCP-1, IL-8, GRO, RANTES, and IP-10, which may critically influence the site-specific recruitment of leukocyte subsets.