Epidermal keratinocytes express the adhesion molecule intercellular adhesion molecule-1 in inflammatory dermatoses

Glycofullerenes Inhibit Particulate Matter Induced Inflammation and Loss of Barrier Proteins in HaCaT Human Keratinocytes

Exposure to particulate matter (PM) has been linked to pulmonary and cardiovascular dysfunctions, as well as skin diseases, etc. PM impairs the skin barrier functions and is also involved in the initiation or exacerbation of skin inflammation, which is linked to the activation of reactive oxygen species (ROS) pathways. Fullerene is a single C₆₀ molecule which has been reported to act as a good radical scavenger. However, its poor water solubility limits its biological applications. The glyco-modification of fullerenes increases their water solubility and anti-bacterial and anti-virus functions. However, it is still unclear whether it affects their anti-inflammatory function against PM-induced skin diseases. Hence, glycofullerenes were synthesized to investigate their effects on PM-exposed HaCaT human keratinocytes. Our results showed that glycofullerenes could reduce the rate of PM-induced apoptosis and ROS production, as well as decrease the expression of downstream mitogen-activated protein kinase and Akt pathways. Moreover, PM-induced increases in inflammatory-related signals, such as cyclooxygenase-2, heme oxygenase-1, and prostaglandin E2, were also suppressed by glycofullerenes. Notably, our results suggested that PM-induced impairment of skin barrier proteins, such as filaggrin, involucrin, repetin, and loricrin, could be reduced by pre-treatment with glycofullerenes. The results of this study indicate that glycofullerenes could be potential candidates for treatments against PM-induced skin diseases and that they exert their protective effects via ROS scavenging, anti-inflammation, and maintenance of the expression of barrier proteins.

Water-Soluble Fullerenol C60(OH)36 toward Effective Anti-Air Pollution Induced by Urban Particulate Matter in HaCaT Cell

Particulate matter (PM), a widespread air pollutant, consists of a complex mixture of solid and liquid particles suspended in air. Many diseases have been linked to PM exposure, which induces an imbalance in reactive oxygen species (ROS) generated in cells, and might result in skin diseases (such as aging and atopic dermatitis). New techniques involving nanomedicine and nano-delivery systems are being rapidly developed in the medicinal field. Fullerene, a kind of nanomaterial, acts as a super radical scavenger. Lower water solubility levels limit the bio-applications of fullerene. Hence, to improve the water solubility of fullerene, while retaining its radical scavenger functions, a fullerene derivative, fullerenol C₆₀(OH)₃₆, was synthesized, to examine its biofunctions in PM-exposed human keratinocyte (HaCaT) cells. The PM-induced increase in ROS levels and expression of phosphorylated mitogen-activated protein kinase and Akt could be inhibited via fullerenol pre-treatment. Furthermore, the expression of inflammation-related proteins, cyclooxygenase-2, heme oxygenase-1, and prostaglandin E2 was also suppressed. Fullerenol could preserve the impaired state of skin barrier proteins (filaggrin, involucrin, repetin, and loricrin), which was attributable to PM exposure. These results suggest that fullerenol could act against PM-induced cytotoxicity via ROS scavenging and anti-inflammatory mechanisms, and the maintenance of expression of barrier proteins, and is a potential candidate compound for the treatment of skin diseases.

Langerhans Cells, Inflammation Markers and Human Papillomavirus Infections in Benign and Malignant Epithelial Tumors from Transplant Recipients

Organ transplant recipients frequently develop warts which progress toward premalignant or malignant lesions after a rather long grafting period. The local immune responses of such lesions (warts, condyloma acuminata, actinic keratoses, Bowen, basal and squamous cell carcinomas) was studied in 32 frozen skin specimens taken from 15 male transplant recipients and compared to similar lesions from the normal population. We studied the expression of T cell subsets, Langerhans cell phenotype, HLA class 1 (beta 2-microglobulin), HLA class 2 (DR antigen), and intercellular adhesion molecule 1 (ICAM 1). The presence of HPV infection was also considered, using in situ hybridization with biotinylated probes in order to examine the correlation with immunological markers. In the dermis, the lesions from grafted patients showed a moderate to intense inflammatory reaction of HLA-DR-positive cells. Most of these cells were CD4+ and CD8+ without any predominance of a single T cell subset. In the epidermis, most lesions were characterized by a reduced number of CD1-positive cells; this was concomitant with a decrease or a loss of beta 2-microglobulin expression by epithelial cells. HLA-DR antigen was not expressed by keratinocytes or tumoral cells in any specimen; ICAM 1 antigen was observed in a few cases. The expression of these markers was similarly modified with or without the presence of HPV DNA. Conversely, most lesions from non-immunocompromised patients, except warts, showed intense inflammatory reactions, with a predominance of CD4-positive cells and large foci of ICAM 1-positive cells. Expression of activation markers by keratinocytes occurred mainly in condylomas and squamous cell carcinomas. In the normal population, HPV infection was only detected in papilloma lesions. These data indicate, in lesions from grafted patients, a lack of effective immune response with partial inhibition of activation markers expressed by keratinocytes. It is conceivable that immunosuppressive treatment with solar exposure may also be responsible for the local immune deficiency and thus for the conversion of benign warts toward malignant lesions in grafted patients.

Balance of apoptotic cell death and survival in allergic diseases

Allergic diseases result from over-reaction of the immune system in response to exogenous allergens, where inflammatory cells have constantly extended longevity and contribute to an on-going immune response in allergic tissues. Here, we review disequilibrium in the death and survival of epithelial cells and inflammatory cells in the pathological processes of asthma, atopic dermatitis, and other allergic diseases.

Pattern of adhesion molecule expression in labial salivary glands from patients with primary Sjögren's syndrome

The aim of this work was to examine the pattern of distribution of adhesion molecules in minor salivary glands from patients with primary Sjögren's syndrome (SS). Labial salivary gland (LSG) biopsies from 31 patients with primary SS and 21 normal subjects were examined. Cryostat sections were examined with monoclonal antibodies to different adhesion molecules using an indirect immunoperoxidase technique. There was an increased expression of ICAM-1, class IMHC, HLA-DR & DQ (p<0.05) on endothelial cells, lymphocytes, fibroblasts and salivary epithelial cells (HLA-DR far exceeds ICAM-1 (limited) epithelial expression). ELAM-1 and to a lesser extent VCAM-1 were demonstrated over some of the endothelial cells in patients, but not in controls (p<0.01). Many of the endothelial cells expressing ICAM-1, DR, DQ, ELAM-1 were high endothelial venules. CD44 was strongly expressed over epithelial cells, endothelial and infiltrating mononuclear cells, while LFA-3 was present mainly on epithelial cells, and faintly on infiltrating inflammatory cells. There was no difference between patients and controls with regard to CD44 or LFA-3 expression. The ligands for the above mentioned adhesion molecules, namely LFA-1α, LFA-1ß, LECAM-1, VLA-4ß(CD49d), CD44 and CD2 were demonstrated (variably) on the surface of infiltrating lymphocytes. CD11b and CD11c were detected over monocytes/macrophages. A proportion of lymphocytes expressed VCAM-1 and CD11c and may function as antigen presenting cells. In some biopsies these molecules were localized at the center of lymphoid follicles with the appearance of dendritic cells. Although the majority of lymphocytes were activated and strongly expressing DR and ICAM-1, they were IL-2Rα (CD25) negative. We conclude that adhesion molecules are prominent in LSG of patients with primary SS. They may play a major role by mediating the lymphocytic infiltration to the glands, retaining the lymphocytes in the glands and regulating the different immune responses in the local microenvironment of this chronic inflammatory disease.

Bacterial superantigen facilitates epithelial presentation of allergen to T helper 2 cells

Although clinical and laboratory evidence support roles for both staphylococcal infection and environmental allergens in the pathogenesis of atopic dermatitis, human studies have largely considered these variables independently. We sought to test the hypothesis that staphylococcal superantigen influences the allergen-specific T cell response. We first mapped a Der p 1 epitope and used HLA DRB1*1501 class II tetramer-based cell sorted populations to show that specific CD4(+) T cells were able to recognize the peptide presented by HLA DR-matched keratinocytes. We observed that staphylococcal enterotoxin B (SEB) enhanced the IL-4 Der p 1-specific T cell response. This response was mediated by two synergistic mechanisms: first, SEB-induced IFN-gamma promoted class II and intercellular adhesion molecule-1 expression by presenting keratinocytes; and second, SEB-induced IL-4 directly amplified allergen-specific CD4(+) T cell production of many cytokines. We propose that handling of staphylococcal infection is a critical step in the amplification of the allergen-specific T cell response, linking two common disease associations and with implications for the prevention and treatment of atopic disease.

alpha-Melanocyte stimulating hormone, inflammation and human melanoma

Alpha-melanocyte stimulating hormone (alpha-MSH) arises from the proteolytic cleavage of proopiomelanocortin (POMC) and is the most potent naturally occurring melanotropic peptide. The biological effects of alpha-MSH are mediated via melanocortin receptors (MCRs), which are expressed in virtually every cutaneous cell type. alpha-MSH has pleiotrophic functions including the modulation of a wide range of inflammatory stimuli such as proinflammatory cytokines, adhesion molecules and inflammatory transcription factors. All of the former would be consistent with a cytoprotective role for this hormone in protecting skin cells from exogenous stress, as would occur following UV exposure or exposure to agents inducing inflammation or oxidative stress. In addition to actions on normal skin cells it also modulates both cutaneous and uveal melanoma cell behavior. With respect to melanoma, alpha-MSH is intriguing as studies have shown that while alpha-MSH has the potential to retard metastatic spread (by reducing cell migration and invasion) it is also capable of reducing the ability of the immune system to detect tumor cells (by down regulating adhesion molecules that would normally assist in immune cell interaction with melanoma cells). This review considers the evolving biology of alpha-MSH and discusses its role in man that extend far beyond pigmentation of skin melanocytes, suggesting that the detoxifying role of alpha-MSH in inducing melanogenesis is only one aspect of the stress-coping role of this hormone. Indeed melanoma cells may owe at least some of their success to the 'protective' role of alpha-MSH.

TNF Inhibition Rapidly Down-Regulates Multiple Proinflammatory Pathways in Psoriasis Plaques

The mechanisms of action of marketed TNF-blocking drugs in lesional tissues are still incompletely understood. Because psoriasis plaques are accessible to repeat biopsy, the effect of TNF/lymphotoxin blockade with etanercept (soluble TNFR) was studied in ten psoriasis patients treated for 6 months. Histological response, inflammatory gene expression, and cellular infiltration in psoriasis plaques were evaluated. There was a rapid and complete reduction of IL-1 and IL-8 (immediate/early genes), followed by progressive reductions in many other inflammation-related genes, and finally somewhat slower reductions in infiltrating myeloid cells (CD11c+ cells) and T lymphocytes. The observed decreases in IL-8, IFN-gamma-inducible protein-10 (CXCL10), and MIP-3alpha (CCL20) mRNA expression may account for decreased infiltration of neutrophils, T cells, and dendritic cells (DCs), respectively. DCs may be less activated with therapy, as suggested by decreased IL-23 mRNA and inducible NO synthase mRNA and protein. Decreases in T cell-inflammatory gene expression (IFN-gamma, STAT-1, granzyme B) and T cell numbers may be due to a reduction in DC-mediated T cell activation. Thus, etanercept-induced TNF/lymphotoxin blockade may break the potentially self-sustaining cycle of DC activation and maturation, subsequent T cell activation, and cytokine, growth factor, and chemokine production by multiple cell types including lymphocytes, neutrophils, DCs, and keratinocytes. This results in reversal of the epidermal hyperplasia and cutaneous inflammation characteristic of psoriatic plaques.

Presentation of ICAM-1 Protein at the Cell Surface of Oral Keratinocytes in the Presence of Adrenomedullin and Corticotrophin

Increasing evidence suggests that adrenomedullin (AM) and corticotrophin (ACTH) are immunomodulatory. Intercellular adhesion molecule-1 (ICAM-1) plays an important role in the recruitment of leukocytes not only from peripheral blood into inflamed tissues but also into epithelia. We have investigated the effects of AM and ACTH on the expression of ICAM-1 by human oral keratinocytes. The human oral keratinocyte cell line H357 was incubated with either AM or ACTH for up to 8 hrs and ICAM-1 expression was measured by cell surface ELISA. ICAM-1 was up regulated by both peptides and this was attenuated by the adenylyl cyclase inhibitor SQ22,536 and the NF-kappaB inhibitor SN-50. H357 cells constitutively express ICAM-1 mRNA and expression of this gene was significantly modulated by AM and ACTH. Furthermore AM caused translocation of NF-kappaB from the cytoplasm to the nucleus. This is the first report describing up regulation of ICAM-1 in oral keratinocytes by AM and ACTH and the results suggest both cAMP and NF-kappaB may play a role. These results further suggest both peptides may have an immunostimulatory role in oral muocsa and skin.

Blockade of T lymphocyte costimulation with cytotoxic T lymphocyte-associated antigen 4-immunoglobulin (CTLA4Ig) reverses the cellular pathology of psoriatic plaques, including the activation of keratinocytes, dendritic cells, and endothelial cells

Efficient T cell activation is dependent on the intimate contact between antigen-presenting cells (APCs) and T cells. The engagement of the B7 family of molecules on APCs with CD28 and CD152 (cytotoxic T lymphocyte-associated antigen 4 [CTLA-4]) receptors on T cells delivers costimulatory signal(s) important in T cell activation. We investigated the dependence of pathologic cellular activation in psoriatic plaques on B7-mediated T cell costimulation. Patients with psoriasis vulgaris received four intravenous infusions of the soluble chimeric protein CTLA4Ig (BMS-188667) in a 26-wk, phase I, open label dose escalation study. Clinical improvement was associated with reduced cellular activation of lesional T cells, keratinocytes, dendritic cells (DCs), and vascular endothelium. Expression of CD40, CD54, and major histocompatibility complex (MHC) class II HLA-DR antigens by lesional keratinocytes was markedly reduced in serial biopsy specimens. Concurrent reductions in B7-1 (CD80), B7-2 (CD86), CD40, MHC class II, CD83, DC-lysosomal-associated membrane glycoprotein (DC-LAMP), and CD11c expression were detected on lesional DCs, which also decreased in number within lesional biopsies. Skin explant experiments suggested that these alterations in activated or mature DCs were not the result of direct toxicity of CTLA4Ig for DCs. Decreased lesional vascular ectasia and tortuosity were also observed and were accompanied by reduced presence of E-selectin, P-selectin, and CD54 on vascular endothelium. This study highlights the critical and proximal role of T cell activation through the B7-CD28/CD152 costimulatory pathway in maintaining the pathology of psoriasis, including the newly recognized accumulation of mature DCs in the epidermis.

T cell-mediated Fas-induced keratinocyte apoptosis plays a key pathogenetic role in eczematous dermatitis

Clinical and histologic similarities between various eczematous disorders point to a common efferent pathway. We demonstrate here that activated T cells infiltrating the skin in atopic dermatitis (AD) and allergic contact dermatitis (ACD) induce keratinocyte (KC) apoptosis. KCs normally express low levels of Fas receptor (FasR) that can be substantially enhanced by the presence of IFN-gamma. KCs are rendered susceptible to apoptosis by IFN-gamma when FasR numbers reach a threshold of approximately 40,000 per KC. Subsequently, KCs undergo apoptosis induced by anti-FasR mAb's, soluble Fas ligand, supernatants from activated T cells, or direct contact between T cells and KCs. Apoptotic KCs show typical DNA fragmentation and membrane phosphatidylserine expression. KC apoptosis was demonstrated in situ in lesional skin affected by AD, ACD, and patch tests. Using numerous cytokines and anti-cytokine neutralizing mAb's, we found no evidence that cytokines other than IFN-gamma participate in this process. In addition, apoptosis-inducing pathways other than FasR triggering were ruled out by blocking T cell-induced KC apoptosis by caspase inhibitors and soluble Fas-Fc protein. Responses of normal human skin and cultured skin equivalents to activated T cells demonstrated that KC apoptosis caused by skin-infiltrating T cells is a key event in the pathogenesis of eczematous dermatitis.

Pine bark extract pycnogenol downregulates IFN-gamma-induced adhesion of T cells to human keratinocytes by inhibiting inducible ICAM-1 expression

Expression of intercellular adhesion molecule-1 (ICAM-1) is necessary for leukocyte/keratinocyte interactions. Upregulation of ICAM-1 expression in keratinocytes has been observed in several inflammatory dermatoses, such as psoriasis, atopic dermatitis, and lupus erythematosus. Inflammatory cytokines, such as interferon-gamma (IFN-gamma), upregulate ICAM-1 expression in keratinocytes. Because of potent antioxidant and anti-inflammatory properties of the French maritime pine bark extract, Pycnogenol (Horphag Research, Geneva, Switzerland), its effects were investigated on the interaction of T cells with keratinocytes after activation with IFN-gamma and the molecular mechanisms involved in such interactions. Studies were performed using a human keratinocyte cell line, HaCaT. Cell adhesion in the presence of IFN-gamma was studied using a coculture assay. Treatment of HaCaT cells with 20 U/ml IFN-gamma for 24 h markedly induced adherence of Jurkat T cells to HaCaT cells. PYC pretreatment (50 microg/ml, 12 h) significantly inhibited IFN-gamma induced adherence of T cells to HaCaT cells (p < .01). ICAM-1 plays a major role in the IFN-gamma-induced adherence of T cells to keratinocytes. Thus, the effect of PYC on IFN-gamma-induced ICAM-1 expression was investigated as well. Pretreatment of HaCaT cells with PYC significantly inhibited IFN-gamma-induced expression of ICAM-1 expression in HaCaT cells. The downregulation of inducible ICAM-1 expression by PYC was both dose and time dependent. A 50 microg/ml dose of PYC and a 12 h pretreatment time (i.e., before activation with IFN-gamma) provided maximal (approximately 70%) inhibition of inducible ICAM-1 expression in HaCaT cells. Gamma-activated sequence present on the ICAM-1 gene confers IFN-gamma responsiveness in selected cells of epithelial origin (e.g., keratinocytes) that are known to express ICAM-1 on activation with IFN-gamma. Gel-shift assays revealed that PYC inhibits IFN-gamma-mediated activation of Stat1, thus suggesting a transcriptional regulation of inducible ICAM-1 expression by PYC. These results indicate the therapeutic potential of PYC in patients with inflammatory skin disorders.

Effect of environmental pollutants on the production of pro-inflammatory cytokines by normal human dermal keratinocytes

The effect of the environmental pollutants, diesel exhaust particles (DEP) and formaldehyde (FA), on the production of pro-inflammatory cytokines (interleukin (IL)-1alpha, IL-1beta, tumor necrosis factor (TNF)-alpha and IL-8) by normal human dermal keratinocytes (hKCs) was investigated. Normal hKCs were incubated with various concentrations of DEP (0.4, 0.8, 4, or 20 microg/ml) or FA (0.25, 0.5, 1, or 5 microg/ml), and cytokine production was then determined by enzyme-linked immunosorbent assay (ELISA). DEP (20 microg/ml) induced IL-1beta production without altering cell growth. The increased production of IL-1beta induced by this concentration of DEP was further enhanced by the presence of phorbol 12-myristate 13-acetate (PMA), although PMA alone did not affect the levels of IL-1beta. IL-8 production was also increased by DEP (0.4 and 0.8 microg/ml), which is consistent with the results that these concentrations of DEP increased the number of cells significantly after 72 h incubation. Although FA alone did not stimulate the production of IL-1beta or IL-8 by keratinocytes, FA (0.5 microg/ml and 5 microg/ml) significantly increased IL-8 and IL-1beta production, respectively, in cells stimulated with PMA. IL-1alpha production was not modulated by FA or DEP even in the presence of PMA. TNF-alpha was produced by unstimulated keratinocytes at barely detectable levels after 48 h incubation. Although basal levels of TNF-alpha in the culture supernatants were increased after stimulation with PMA, neither pollutant alone nor combination with PMA affected the levels of TNF-alpha. These in vitro findings suggest that environmental pollutants may act as modulating factors of cutaneous inflammation by affecting the ability of keratinocytes to release pro-inflammatory cytokines.

Retinoic acid potentiates TNF-alpha-induced ICAM-1 expression in normal human epidermal keratinocytes

ICAM-1 protein in keratinocytes is thought to contribute to cutaneous inflammatory reactions. Its induction depends-among others-on cytokines such as TNF-alpha, IFN-gamma, IL-1 or on retinoic acid (RA), a key regulator of epidermal homeostasis. We investigated the effect of treatments with TNF-alpha, RA or their combination on ICAM-1 expression on proliferative or differentiating keratinocytes over an 8 day culture period. Basal ICAM-1 levels were undetectable at low (30 microM) and standard (88 microM) Ca2+ and RA alone did not induce ICAM-1. However, at high Ca2+ (1500 microM), ICAM-1 levels were augmented in response to RA-treatment. TNF-alpha induced a transient ICAM-1 increase in NHK, which reached peak-levels 2-4 days post cytokine stimulus. RA potentiated the TNF-alpha-induced ICAM-1 response in all Ca2+-concentrations. This potentiating effect of RA was confirmed at the mRNA level. In summary, our results establish retinoic acid as an enhancer of TNF-alpha-induced ICAM-1 levels in NHK.

Role of T cells in atopic dermatitis. New aspects on the dynamics of cytokine production and the contribution of bacterial superantigens

Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disease. Influx of activated T cells into the skin lesions represents a hallmark in AD. Recent results indicate a dynamic T-cell-derived cytokine production in AD. In addition to the well-known TH-2 component, chronic lesions and late-phase allergic responses are characterized by an TH-1/TH-0 cytokine pattern. Although there is no doubt that aeroallergens can contribute to the elicitation of acute- and late-phase allergic responses in AD, their role in the immunopathogenesis is controversally discussed. Recent attention has been given to the long-known phenomenon of persistent colonization of AD skin with S. aureus and the potential role of S. aureus-derived superantigens. Evidence from several in vitro and in vivo studies suggests that such bacterial superantigens have the potency to trigger chronic T-cell-mediated skin inflammation. Although these data are certainly suggestive, further clinical studies are required to elucidate the role of bacterial superantigens in initiation, maintenance and, especially, chronicity of skin inflammation.

Effects of topical calcipotriol on the expression of adhesion molecules in psoriasis

Seven patients with chronic plaque psoriasis were treated with topical calcipotriol for 8 to 24 weeks; the lesions improved in 5 patients. Immunohistochemistry was performed on frozen sections, to evaluate the expression of adhesion molecules and extracellular matrix components before and after therapy. Changes in expression and topography of beta1 and beta4 integrins were found on psoriatic lesions before therapy and a reduction in the expression of tenascin was detected as well. Moreover, several activation markers such as ICAM-1, HLA-DR, CD26 were focally positive, with a diffuse cytoplasmic reactivity, in basal and suprabasal layers in untreated lesions. In the 5 patients in whom lesions regressed after topical calcipotriol treatment, we observed a histological normalization of the epidermis and the inflammatory infiltrate was reduced. Moreover, not only was there a normalization in the expression and topography of adhesion molecules, but also the integrin pattern observed after therapy was superimposable to that of normal skin.

Monitoring of disease activity by measurement of inflammatory markers in atopic dermatitis in childhood

Serum levels of soluble interleukin-2 receptor (sIL-2R), intercellular adhesion molecule-1 (ICAM-1), endothelial leukocyte adhesion molecule (ELAM-1), and eosinophil cationic protein (ECP) were measured in 20 patients with atopic dermatitis before and after 4 days' treatment with prednisolone p.o. as well as in 16 healthy, nonatopic controls. Before steroid treatment, patients with atopic dermatitis demonstrated significantly higher serum levels of sIL-2R, ICAM-1, and ECP than healthy controls (P < 0.001), whereas ELAM-1 levels were not different between the groups. After 4 days of steroid treatment, clinical improvement was associated with a decrease of sIL-2R (P < 0.003), ICAM-1 (P < 0.004), and ECP serum levels (P < 0.003), but ELAM-1 levels remained unchanged. Both serum ECP and sIL-2R levels were significantly correlated with disease severity before as well as after steroid treatment. Changes of sIL-2R concentrations were strongly related to the changes of ECP levels. In addition, changes of serum sIL-2R and ECP levels in percentage were correlated with clinical improvement. These results indicate that the determination of sIL-2R and ECP serum levels may be useful in monitoring disease activity in atopic dermatitis in childhood, especially in treatment trials.

The expression of cytokines, growth factors and ICAM-1 in the healing of human cutaneous xenografts on nude mice

We postulate that wound healing is an orderly process mediated by a programmed expression of cytokines and growth factors. We suggest that these factors are produced in a consistent sequence, in regulated quantities and eliminated when their function is complete. We report here the results of studies on several cytokines, growth factors and the intercellular adhesion molecule expressed during the healing of grafts were visible clinically around 3-5 days post-graft and were completed by 4 weeks post-graft. During the 1st 2 weeks, we observed the following. (i) K-14 keratin was prominent throughout the entire epidermis. Thereafter it was limited to basal cell layers. (ii) Langerhans cells were not detectable with anti-human CD1a antibodies during the first week of healing but were clearly detectable 2 weeks post-graft. (iii) DOPA (dihydroxy phenylalanine) positive melanocytes gradually increased with time. The epidermis 21 to 28 days post-graft clinically and histologically seemed to be morphologically intact. Interleukin-1 (IL-1) was clearly detected in some basal cells of the epidermis, especially in melanocytes and some keratinocytes during the early stage of healing. Transforming growth factor-alpha (TGF-alpha) was detected in epidermis first in melanocytes and some keratinocytes shortly after grafting and again in the late stage of healing. It was also found in some dermal cells. Its expression coincided with keratinocyte proliferation and melanocyte migration. TGF-beta was strongly expressed in the epidermis and dermis after the first week post graft. (iv) ICAM-1 was transiently expressed only at the onset of healing. We previously reported that pro-opiomelanocortin and its derivatives MSH/ ACTH are expressed strongly during the healing of human xenografts. The 4 additional molecules which are the subject of this report all are expressed in healing human skin in a predictable sequence and quantity (intensity of stain). Together these data support our hypothesis that healing is a highly regulated process mediated by numerous cytokines.

Dermal injection of immunocytes induces psoriasis

Establishing direct and causal relationships among the confederacy of activated cell types present in psoriasis has been hampered by lack of an animal model. Within psoriatic plaques there are hyperplastic keratinocytes, infiltrating immunocytes, and activated endothelial cells. The purpose of this study was to determine if psoriasis is primarily a disorder of keratinocytes or the immune system. Using a newly developed experimental system in which full-thickness human skin is orthotopically transferred onto severe combined immunodeficient mice, autologous immunocytes were injected into dermis, and the resultant phenotype characterized by clinical, histologic, and immunophenotypic analyses. Engraftment of samples included both uninvolved/ symptomless (PN) skin removed from patients with psoriasis elsewhere, or from healthy individuals with no skin disease (NN skin). In 10 different experiments involving 6 different psoriasis patients, every PN skin was converted to a full-fledged psoriatic plaque skin by injection of autologous blood-derived immunocytes. In all but one psoriatic patient, the immunocytes required preactivation with IL-2 and superantigens to convert PN skin into psoriatic plaque skin. In every case, resultant plaques were characterized by visible presence of flaking and thickened skin, loss of the granular cell layer, prominent elongation of rete pegs with a dermal angiogenic tissue reaction, and infiltration within the epidermis by T cells. Lesional skin displayed 20 different antigenic determinants of the psoriatic phenotype. None of the four NN skin samples injected with autologous immunocytes converted to psoriatic plaques. We conclude that psoriasis is caused primarily by the ability of pathogenetic blood-derived immunocytes to induce secondary activation and disordered growth of endogenous cutaneous cells including keratinocytes and vascular endothelium.

Modulation of epidermal differentiation, tissue inflammation, and T-lymphocyte infilitration in psoriatic plaques by topical calcitriol

Psoriasis is characterized by immune activation, increased proliferation and abnormal differentiation of keratinocytes. The reported anti-psoriatic mechanisms of action in vivo of vitamin D analogues include reduction of keratinocyte proliferation and induction of keratinocyte terminal differentiation. We investigated whether the anti-psoriatic effect of the natural active vatamin D analogue, calcitriol, applied topically, is due to direct effects on keratinocytes alone or also due to immunoregulatory effects of calcitriol. Psoriasis patients were treated with topical calcitriol (0.005%) and a vehicle control for 8 weeks. Disease activity was assessed by a severity index and quantitative histopathological markers. In vitro studies of lymphocyte proliferation and gamma interferon secretion and of keratinocyte proliferation complemented the clinicohistopathologic studies. A heterogeneous response to calcitriol treatment could be segregated based upon elimination of K-16 keratin expression. Calcitriol treatment decreased keratinocyte proliferation, normalized keratinocyte differentiation and decreased immune activation in plaques. The histologic response to vitamin D treatment of psoriasis includes suppression of both immune and keratinocyte activation in situ. These studies provide a basis for rational combination of anti-psoriatic treatments and for the design of new vitamin D analogues to treat psoriasis.

FK506 and cyclosporin A inhibit growth factor-stimulated human keratinocyte proliferation by blocking cells in the G0/G1 phases of the cell cycle

FK506, a new immunosuppressive agent, is effective in treating patients with psoriasis. A major feature of psoriasis vulgaris is the hyperproliferation of keratinocytes together with inflammation. To determine the effect of FK506 or cyclosporin A (CsA) on the keratinocyte cell cycle, flow cytometry and the growth factor free normal human keratinocyte-arrested system were used to assess keratinocyte proliferation. FK506 and CsA inhibit keratinocyte proliferation induced by EGF, TGF-alpha or IL-6. The antiproliferative effects of FK506 and CsA directly correlated with blockade of the keratinocyte cell cycle at the G0/G1 phases. These findings might indicate that the effects of FK506 and CsA on proliferation of cultured normal human keratinocytes are probably related to direct effects on growth regulation of keratinocytes via EGF, TGF-alpha or IL-6 stimulation.

The role of alpha E beta 7 integrin (CD103) and E-cadherin in epidermotropism in cutaneous T-cell lymphoma

Adhesion molecules such as integrins and cadherins are thought to play a critical role in T-cell migration and localization within the epidermis (epidermotropism). The purpose of this study was to correlate T-cell expression of the integrin CD103 and E-cadherin in cutaneous T-cell lymphoma (CTCL). Serial sections of skin biopsies from 22 patients with CTCL and 13 with benign reactive dermatitis were stained with antibodies to CD4, CD103, and E-cadherin by the avidin-biotin peroxidase technique. CD103 was expressed on single epidermotropic CD4+ T-cells in 9/9 early stage (patch/plaque) CTCL and 6/10 reactive dermatitis biopsies. Less than 30% of dermal T-cells expressed CD103. All 4/4 late stage (tumor) CTCL were CD103-. Epidermal aggregates of CD4+ T-cells (Pautrier's microabscesses) were CD103-. E-cadherin was expressed on epidermal keratinocytes and follicular and sweat gland epithelia but not on T-cells. We conclude that CD103 expression on cutaneous T-cells parallels the degree of epidermotropism exhibited in both neoplastic and inflammatory disorders of the skin. E-cadherin is not expressed on T-cells infiltrating the skin. Further investigation is necessary to further elucidate the interaction between CD103 and E-cadherin in facilitating trafficking of T-cells into the epidermis.

Heterogeneity of ICAM-1 expression, and cytokine regulation of ICAM-1 expression, in skin and oral keratinocytes

Differences in expression of intercellular adhesion molecule-1 (ICAM-1) and ICAM-1 mRNA levels were studied in cultured skin and oral keratinocytes before and after stimulation with different pro-inflammatory cytokines. Basal expression of ICAM-1 was undetectable on skin keratinocytes but oral keratinocytes expressed ICAM-1 at high levels. Interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) increased ICAM-1 expression on both cell types, although TNF-alpha had a greater effect on oral than skin keratinocytes (P<0.05) and IFN-gamma was more effective than TNF-alpha on both cell types (P<0.01). In combination, TNF-alpha and IFN-gamma synergistically increased ICAM-1 expression on skin keratinocytes only, although ICAM-1 mRNA was synergistically increased in both cell types. IL-1alpha and IL-1beta induced a small increase in ICAM-1 expression on oral keratinocytes but had no effect on skin keratinocytes.

Intercellular adhesion molecule-1

The intercellular adhesion molecule (ICAM) 1 is an Ig-like cell adhesion molecule expressed by several cell types, including leukocytes and endothelial cells. It can be induced in a cell-specific manner by several cytokines, for example, tumor necrosis factor-alpha, interleukin-1, and interferon-gamma, and inhibited by glucocorticoids. Its ligands are the membrane-bound integrin receptors LFA-1 and Mac-1 on leukocytes, CD43, the soluble molecule fibrinogen, the matrix factor hyaluronan, rhinoviruses, and Plasmodium falciparum malaria-infected erythrocytes. ICAM-1 expression is predominantly transcriptionally regulated. The ICAM-1 promoter contains several enhancer elements, among them a novel kappa B element which mediates effects of 12-O-tetradecanoylphorbol-13-acetate, interleukin-1, lipopolysaccharide, tumor necrosis factor-alpha, and glucocorticoids. Expression regulation is cell specific and depends on the availability of cytokine/hormone receptors, signal transduction pathways, transcription factors, and posttranscriptional modification. ICAM-1 plays a role in inflammatory processes and in the T-cell mediated host defense system. It functions as a costimulatory molecule on antigen-presenting cells to activate MHC class II restricted T-cells, and on other cell types in association with MHC class I to activate cytotoxic T-cells. ICAM-1 on endothelium plays an important role in migration of (activated) leukocytes to sites of inflammation. ICAM-1 is shed by the cell and detected in plasma as sICAM-1. Regulation and significance of sICAM-1 are as yet unclear, but sICAM-1 is increased in many pathological conditions. ICAM-1 may play a pathogenetic role in rhinovirus infections. Derangement of ICAM-1 expression probably contributes to the clinical manifestations of a variety of diseases, predominantly by interfering with normal immune function. Among these are malignancies (e.g., melanoma and lymphomas), many inflammatory disorders (e.g., asthma and autoimmune disorders), atherosclerosis, ischemia, certain neurological disorders, and allogeneic organ transplantation. Interference with ICAM-1 leukocyte interaction using mAbs, soluble ICAM-1, antisense ICAM-1 RNA, and in the case of melanoma mAb-coupled immunotoxin, may offer therapeutic possibilities in the future. Integration of knowledge concerning membrane-bound and soluble ICAM-1 into a single functional system is likely to contribute to elucidating the immunoregulatory function of ICAM-1 and its pathophysiological significance in various disease entities.

The ICAM-3/LFA-1 interaction is critical for epidermal Langerhans cell alloantigen presentation to CD4+ T cells

Intercellular adhesion molecule (ICAM)-3 is a recently described member of the immunoglobulin superfamily and, as such, is closely related to ICAM-1 and ICAM-2. All three ICAMS are cognate for the counter-receptor lymphocyte function associated antigen-1 (LFA-1, CD11a/CD18). Unlike ICAM-1 and ICAM-2, ICAM-3 is constitutively expressed at high levels on resting leucocytes. We investigated the expression and function of ICAM-3 in normal skin (n = 5), as well as its expression in psoriasis (n = 4), atopic eczema (n = 4), allergic (rhus) contact dermatitis (n = 3), and cutaneous T-cell lymphoma (CTCL, n = 2). Five-micrometre cryostat sections of skin were stained using monoclonal antibodies to ICAM-3 and a well characterized immunoperoxidase technique. In normal skin, ICAM-3 was expressed by all cutaneous leucocytes but most striking was the strong expression of ICAM-3 by Langerhans cells within both epidermis and dermis. This observation was confirmed by double-labelling with CD1a and negative staining with an IgG1 isotype control. In psoriasis, atopic eczema, allergic contact dermatitis, and CTCL, ICAM-3 was co-expressed on all CD1a+ cells, although, in psoriasis, the intensity of ICAM-3 expression was reduced. Functional blocking experiments were performed to determine whether the observed ICAM-3 expression on Langerhans cells was functionally important in antigen presentation. CD4+ T cells were prepared from peripheral blood and 10(5) CD4+ T cells combined with 10(5) epidermal cells harvested from keratome biopsies of normal skin of an individual allogeneic to the T-cell donor. Addition of 50 micrograms anti-ICAM-3 to the co-culture resulted in a consistent (50%) reduction in degree of alloantigen presentation by Langerhans cells to T cells. Inhibition was 77% of that produced by the addition of anti-LFA-1. These data indicate that ICAM-3 is constitutively expressed by Langerhans cells and is a major ligand for LFA-1 on CD4+ T cells during their response to Langerhans cells. Because fresh Langerhans cells constitutively express little ICAM-1, whereas ICAM-3 is constitutively expressed at high levels, it would appear that ICAM-3 is the dominant functional ICAM on in situ Langerhans cells in the normal epidermis.

Expression of ICAM-3/CD50 in normal and diseased skin

ICAM-3 is a newly recognized adhesion molecule, which is a member of the immunoglobulin supergene family of ICAMs, and has been shown to be identical with the CD50 antigen. Recent functional studies have shown that ICAM-3 is a ligand for LFA-1, and plays an important part in immune reactions. To date, very few data exist in the literature concerning its expression in the skin. In the present study, we investigated the expression of ICAM-3 in normal skin and in 98 biopsy specimens of various inflammatory and neoplastic dermatoses. ICAM-3 was found to be expressed by epidermal CD1a+ Langerhans cells, by cells of Langerhans cell histiocytosis, by T and B lymphocytes infiltrating the dermis in cutaneous lymphomas and in a wide spectrum of inflammatory dermatoses. Epidermal keratinocytes were consistently negative; endothelial expression of ICAM-3 was observed in six of the 98 cases. These results show that ICAM-3 is constitutively and widely expressed by cells participating in inflammatory dermatoses (including Langerhans cells and T and B lymphocytes), and that it can be, albeit rarely, induced on endothelial cells and dermal dendrocytes. These results highlight the important part that ICAM-3 may play in cutaneous inflammatory and immune reactions.

Intralesional T-lymphocyte activation as a mediator of psoriatic epidermal hyperplasia

An early cellular event in the development of psoriatic lesions is infiltration of target tissue by macrophages and activated T lymphocytes. Lesional psoriatic skin contains activated memory T lymphocytes with production of mRNA for lymphokines such as interleukin-2, interferon-gamma, and tumor necrosis factor-alpha that is elevated relative to normal or uninvolved psoriatic skin. That the T-cell activation and cellular lymphokine production have a crucial role in the maintenance of epidermal hyperplasia in the psoriatic lesion is indicated by the beneficial effect of immunosuppressive agents in the treatment of psoriasis (cyclosporin A, FK506, anti-CD3, anti-CD4). A link between immune activation and psoriasis is also indicated by immunogenetic associations in this disease. Also, psoriatic keratinocytes appear to have been modulated by T-cell lymphokines in vivo, because they abnormally express molecules uniquely induced on keratinocytes by the T-cell product interferon-gamma. Indeed, T cells producing interferon-gamma have been cloned from psoriatic lesions, and they are able to induce keratinocyte class II major histocompatibility complex and intercellular adhesion molecule expression. These lesion-derived T-cell clones can induce growth of keratinocytes, and specifically lesional psoriatic T cells produce factors that induce increased keratinocyte colony formation, as well as increased cell cycle entry of the normally quiescent stem cell population. Interferon-gamma, although a growth inhibitor on its own, acts cooperatively with other T-cell-produced growth factors to cause keratinocyte growth induction. Furthermore, relative to normal stem cells, keratinocyte stem cells (beta 1 integrin+ K1/K10-) in psoriatic uninvolved epidermis are significantly hyperresponsive to the growth-stimulatory lymphokine milieu created by lesional T lymphocytes. Whether such abnormalities in responsiveness are associated with new genetic linkages reported in families of psoriasis patients is unknown. As the epidermis of lesional psoriatic skin can be demonstrated to produce elevated levels of factors that can further potentiate T-cell activation, a self-sustaining cycle can be constructed of T-cell recruitment, intralesional activation, release of factors that preferentially stimulate psoriatic epidermal stem cells to proliferate, and further epidermal potentiation of the T-cell-mediated lesions.

The development of manifest psoriatic lesions is linked with the appearance of ICAM-1 positivity on keratinocytes

The development of psoriatic lesions was studied in 36 psoriatic patients using the Koebner reaction induced by tape stripping. Two biopsies per patient were taken from non-lesional psoriatic skin before, and 6 h, 2 days, 7 days, 14 days and 21 days after tape stripping. Alterations in HLA-DR, ICAM-1, Ki-67 and FXIIIa positivities in both the dermis and the epidermis were estimated using immunohistochemical methods. A double staining for CD4+ and CD8+ T cells was also carried out to show their possible Ki-67 positivity. Results were compared with those from lesional (mature plaque) and non-lesional psoriatic skin, and control skin. Of the 36 patients, 9 were Koebner-positive. The most important finding in Koebner-positive psoriatic skin was the appearance of ICAM-1 positivity on epidermal keratinocytes simultaneously with the clinically observed lesion on day 7. The number of FXIIIa+ dendrocytes in the dermis was quite constant, and increased in mature psoriatic lesions only. The number of active HLA-DR+ immunocompetent cells increased in developing psoriatic lesions, being highest in mature lesions, but no Ki-67 positivity was detected in epidermal or dermal T cells in the psoriatic specimens. Based on these results, it is concluded that T cells divide and are activated extracutaneously in psoriasis, and also that ICAM-1/LFA-1 interactions are important in the recruitment of inflammatory cells and in controlling the effector cell functions.

Immunolocalization of adhesion molecules in psoriatic arthritis, psoriatic and normal skin

Adhesion molecule expression in synovial membrane obtained from patients with psoriatic arthritis (PA) has previously been compared with rheumatoid arthritis (RA). Although expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was similar in both psoriatic and rheumatoid synovium, in contrast, little or no endothelial leucocyte adhesion molecule-1 (ELAM-1) was observed in psoriatic synovium. In the present study, the expression of ICAM-1, ELAM-1 and VCAM-1 was examined in the involved and uninvolved skin from patients with PA (n = 15), patients with psoriasis (Ps) but no arthritis (n = 5) and in normal skin (n = 4). ICAM-1 was intensely expressed on endothelium and keratinocytes of involved skin from patients with Ps with or without arthritis. There was constitutive expression of ICAM-1 on endothelium only in uninvolved and normal skin. In contrast, ELAM-1 expression was restricted to endothelial cells; it was widespread and intense in involved skin, but was minimal in uninvolved and normal skin. VCAM-1 was expressed on endothelium, and also on some dendritic cells in involved psoriatic skin. There was minimal VCAM-1 staining on endothelial cells in uninvolved and normal skin. In conclusion, in involved psoriatic skin from patients with and without arthritis ICAM-1, ELAM-1 and VCAM-1 expression is up-regulated on vascular endothelium, and ICAM-1 is expressed on keratinocytes. However, ELAM-1 and VCAM-1 expression seen in dermal vessels is not found in psoriatic synovial vessels. These differences suggest a mechanism for controlling cellular traffic in Ps and in PA.

Kinetics and regulation of human keratinocyte stem cell growth in short-term primary ex vivo culture. Cooperative growth factors from psoriatic lesional T lymphocytes stimulate proliferation among psoriatic uninvolved, but not normal, stem keratinocytes

Flow cytometric analysis of primary ex vivo keratinocyte cultures demonstrated that stem cells, (beta 1 integrin+, keratin 1/keratin 10 [K1/K10-], proliferating cell nuclear antigen [PCNA-] [Bata-Csorgo, Zs., C. Hammerberg, J. J. Voorhees, and K. D. Cooper. 1993. J. Exp. Med. 178:1271-1281]) establish such cultures. This methodology also enabled the quantitation of synchronized recruitment of these cells from G0 into G1 of the cell cycle (PCNA expression), which preceded bright beta 1 integrin expression. (beta 1 integrinbright expression has been shown to be a characteristic feature of keratinocyte stem cells in culture (Jones, P. H., and F. M. Watt. 1993. Cell. 73:713-724). Using the above assay, we determined whether lesional T lymphocytes in psoriasis could be directly responsible for the induction of the stem cell hyperproliferation that is characteristic of this disease. Indeed, CD4+ T lymphocytes, cloned from lesional psoriatic skin and stimulated by immobilized anti-CD3 plus fibronectin, promoted psoriatic uninvolved keratinocyte stem cell proliferation via soluble factors. This induction appeared to be through accelerated recruitment of stem cells from their quiescent state (G0) into cell cycle. By contrast, normal keratinocyte stem cells exhibited no such growth stimulation. Supernatants exhibiting growth induction all contained high levels of GM-CSF and gamma-IFN, low IL-3 and TNF-alpha, and variable IL-4. Only anti-gamma-IFN antibody was able to neutralize growth stimulatory activity of the supernatants on psoriatic uninvolved keratinocyte stem cells. However, because recombinant gamma-IFN alone inhibited growth in this assay, these data suggest that, in psoriasis, gamma-IFN acts cooperatively with other growth factors in the immune induction of cell cycle progression by the normally quiescent stem cell keratinocytes.

Evidence that regression in keratoacanthoma is immunologically mediated: a comparison with squamous cell carcinoma

Recent research observations suggest that the keratoacanthoma (KA) is a form of resolving squamous cell carcinoma (SCC). The mechanism by which this resolution takes place has not been fully explored, although it may have an immunological basis. To investigate this, we compared 15 clinically and histologically diagnosed KAs and 15 SCCs with regard to cellular infiltrate and keratin expression. We found that KAs have significantly higher numbers of CD3+ and CD4+ cells invading their epidermal component than SCCs. The T lymphocytes infiltrating KAs were more immunologically active, as greater numbers expressed the interleukin-2 receptor (IL-2R) than those in SCCs. It is of interest that CD36 was expressed by a significantly greater proportion of tumour cells within KAs than SCCs. This was also the case for the intercellular adhesion molecule ICAM-1, and the differentiation marker keratin 10. Overall, these findings suggest that KA regression is immunologically mediated, with activated (IL-2R+) CD4+ T lymphocytes and adhesion molecules playing a pivotal role in the immune response.

Similar ectopic expression of ICAM-1 and HLA class II molecules in hypertrophic scars following thermal injury

In previous studies we have shown that HLA Class II antigens are expressed by keratinocytes and fibroblasts in hypertrophic scars. Because of the potential role of immunological events in the pathogenesis of hypertrophic scars, in the present study we have tested hypertrophic scars for the expression of intercellular adhesion molecule-1 (ICAM-1), a molecule which plays an important role in immunological phenomena. Immunoperoxidase staining with anti-ICAM-1 MoAb of 10 hypertrophic scar samples detected this molecule on epidermal keratinocytes and on about 30 per cent of fibroblasts at the site of lymphoid infiltration. The expression of ICAM-1 in hypertrophic scars was similar to that of HLA Class II antigens. Since the concomitant expression of ICAM-1 and HLA Class II by keratinocytes is known to enhance their antigen-presenting properties, the present results support the possibility that immunological events play a role in the disruption of the normal processes of wound healing and tissue remodelling which result in hypertrophic scars.

Comparison of cell adhesion molecule expression in cutaneous leucocytoclastic and lymphocytic vasculitis

AIMS

To compare the expression of the cell adhesion molecules intercellular adhesion molecule-1 (ICAM-1), ELAM-1 (E-selectin), and vascular cell adhesion molecule-1 (VCAM-1) in cutaneous leucocytoclastic and lymphocytic vasculitis.

METHODS

Immunohistochemical analysis was performed on early lesional skin biopsy specimens of leucocytoclastic vasculitis (n = 14), lymphocytic vasculitis (n = 10), non-lesional skin (n = 12), and normal skin (n = 5). A standard immunoperoxidase technique was used to detect expression of ICAM-1, E-selectin, VCAM-1, and the cell markers CD11a, CD11b, CD11c, von Willebrand factor, CD3, CD68, and neutrophil elastase (NP57).

RESULTS

Basal keratinocyte intercellular adhesion molecule-1 was expressed in eight (80%) cases of lymphocytic and in only one (7%) case of leucocytoclastic vasculitis, and not in non-lesional skin or control biopsy specimens from normal subjects. E-selectin was expressed on vascular endothelium in eight (57%) cases of leucocytoclastic and in seven (70%) cases of lymphocytic vasculitis. Endothelial vascular cell adhesion molecule-1 expression was seen in three (21%) biopsy specimens of leucocytoclastic and five (50%) of lymphocytic vasculitis. There were increased numbers of cells in the dermal infiltrate stained for NP57, CD11b, and CD11c in leucocytoclastic compared with lymphocytic vasculitis (p < 0.001, p = 0.013, p = 0.009, respectively); immunoreactive positive cells for CD3 and CD11a were increased in lymphocytic compared with leucocytoclastic vasculitis (p < 0.001, p = 0.011, respectively).

CONCLUSIONS

These observations indicate that upregulation of adhesion molecule expression occurs in both leucocytoclastic and lymphocytic vasculitis. The different patterns of adhesion molecule expression in the two groups of vasculitis may reflect differences in the local release of cytokines. In particular, detection of intercellular adhesion molecule-1 expression by keratinocytes in lymphocytic vasculitis is consistent with an active role for mediators derived from T lymphocytes in the pathogenesis of the lesion.

Ultraviolet-A radiation induces adhesion molecule expression on human dermal microvascular endothelial cells

Ultraviolet radiation is capable of inducing numerous skin reactions. Considerable amounts of UVA radiation penetrate the epidermis and reach the microvascular endothelium of the papillary dermis. In order to investigate putative direct effects of UV radiation on endothelial cells, we studied adhesion molecule expression by immunostaining procedures and FACS analysis, following irradiation of normal human skin and cultured human dermal endothelial cells. Enhanced immunostaining for ICAM-1 and E-selectin was detected in biopsies taken after in vivo UVA and UVB irradiation, compared with non-irradiated control skin. On cultured human dermal endothelial cells, however, ICAM-1 and E-selectin were inducible by UVA but not UVB. The induction was dose-dependent, peaking at 20 J/cm2 for both adhesion molecules, and time-dependent, peaking after 6 and 24 h for E-selectin and ICAM-1, respectively. Expression of VCAM-1 and PECAM/EndoCAM/CD31 was unaffected by any UV-radiation modality. The functional integrity of irradiated cells was monitored by an exclusion assay of the fluorescent dye 7-AAD, and by staining for the cytoskeletal proteins actin and vimentin. Our results demonstrate that dermal microvascular endothelial cells are a critical and direct target of UVA, and suggest they may play a pivotal role in UV-induced inflammatory skin conditions.

Endothelial cell adhesion molecules in psoriasis

Skin biopsies from patients with psoriasis and normal controls were examined for the expression of cell adhesion molecules including intercellular adhesion molecule-1 (ICAM-1), endothelial leukocyte adhesion molecule-1 (ELAM-1), HECA-452 and 4D10, using an immunoperoxidase techique. This study demonstrates that psoriatic skin exhibits a wide variety of markers of endothelial cell activation which are either induced or increased in expression (ICAM-1, ELAM-1 & 4D10). Moreover, ICAM-1 & HECA-452 are also expressed on leukocytes. These antigens may facilitate the adhesion of inflammatory cells to endothelium and antigen-presenting cells in psoriatic skin. Thus, they may play a role in faciliating the infiltration of leukocytes into psoriatic skin.

PUVA bath therapy strongly suppresses immunological and epidermal activation in psoriasis: a possible cellular basis for remittive therapy

Psoriasis is characterized by alterations in both the epidermis and dermis of the skin. Epidermal keratinocytes display marked proliferative activation and differentiate along an "alternate" or "regenerative" pathway, while the dermis becomes infiltrated with leukocytes, particularly interleukin 2 (IL-2) receptor-bearing "activated" T cells. Psoralens, administered by the oral route, have therapeutic effects in psoriasis when photochemically activated by ultraviolet A light (PUVA therapy). Recently psoralen bath therapy has been introduced to more effectively deliver this agent to the diseased skin. We have correlated the efficacy of PUVA bath therapy with its effects on specific molecular and cellular parameters of disease, in 10 consecutive patients with recalcitrant psoriasis. Rapid clearing of lesions occurred in 8 out of 10 patients. Biopsies were taken from lesional and nonlesional skin before and after a single round of therapy, and observation was continued in our Clinical Research Center at The Rockefeller University. Enumeration of cycling keratinocytes with the Ki-67 monoclonal antibody showed that PUVA reduced cell proliferation by 73%. The pathological increase in insulin-like growth factor 1 (IGF-1) receptors was reversed, whereas epidermal growth factor (EGF) receptors, which are also increased in psoriasis, remained unchanged. Keratinocyte proteins that are expressed in abnormal sites of the epidermis during psoriasis, i.e., keratin 16, filaggrin, and involucrin, were, after PUVA treatment, localized to their normal sites. Epidermal and dermal T-lymphocytes (CD3+), as well as CD4+, CD8+, and IL-2 receptor+ subsets, were strongly suppressed by PUVA, with virtual elimination of IL-2 receptor+ T cells in some patients. Consistent with diminished lymphocyte activation, HLA-DR expression by epidermal keratinocytes was markedly reduced in treated skin. In comparison to cyclosporine treatment of psoriasis, PUVA therapy leads to more complete reversal of pathological epidermal and lymphocytic activation, changes which we propose to be the cellular basis for a more sustained remission of disease after PUVA treatment.

Human epidermal keratinocytes are a source of soluble ICAM-1 molecules

A soluble form of the usually membrane-bound adhesion molecule ICAM-1 was detected in supernatants derived from human epidermal keratinocytes. Specifically, supernatants harvested from long-term cultured normal human keratinocytes, or from the spontaneously immortalized keratinocyte cell line HaCaT, did not contain significant amounts of sICAM-1, but shedding of sICAM-1 was found to be markedly induced upon stimulation of keratinocytes with rh IFN gamma. In contrast, cells from the two epidermoid carcinoma cell lines, KB and A431, constitutively shed significant amounts of sICAM-1 even without cytokine stimulation, and sICAM-1 contents in supernatants harvested from these cells were further increased upon stimulation of cells with rh IFN gamma. These studies indicate, that in addition to peripheral blood mononuclear cells and human melanoma cells, human epidermal keratinocytes constitute an important cellular source of sICAM-1. By binding to leukocyte LFA-1 molecules, keratinocyte-derived sICAM-1 may influence inflammatory responses in the skin. In addition, constitutive shedding of sICAM-1 by transformed human keratinocytes may represent a possible mechanism by which neoplastic keratinocytes escape from cytotoxicity.

IL-1 alpha-induced expression of ICAM-1 on cultured hyperproliferative keratinocytes: suppression by antipsoriatic dimethyl-fumarate

BACKGROUND

In the psoriatic plaque both IL-1 dysregulation and ICAM-1 expression on keratinocytes have been previously described. Furthermore systemic administration of fumarates has been reported to be effective in psoriasis. We, therefore, studied the effect of dimethyl-fumarate ester (DMF) on the putative IL-1-induced ICAM-1 expression.

METHODS

Hyperproliferative human keratinocytes (HaCaT cell line) were incubated in 10 to 100 U/mL IL-1 alpha for 24 h with and without preincubation with 0.4-12.0 microM DMF: Expression of ICAM-1 was measured by a special ELISA-APAAP technique.

RESULTS

The exposure to IL-1 led to a significant dose-dependent induction of ICAM-1 expression of from 124 +/- 17 to 194 +/- 22% (control 100 +/- 12%), while proliferation remained unaltered. Pretreatment with > or = 4 microM DMF resulted in a distinct suppression of ICAM-1 expression and a slight decrease in proliferation.

CONCLUSIONS

The present results show that ICAM-1 expression on hyperproliferative keratinocytes may be triggered by IL-1 alpha and serve as a molecular target for antipsoriatic DMF.

Interleukin-4 and interferon-gamma interactions in the induction of intercellular adhesion molecule-1 and major histocompatibility complex class II antigen expression of normal human keratinocytes

Interleukin-4 (IL-4) that may be produced by T-helper cells in atopic lesions has immunomodulatory activities on skin cells which are poorly known. Our study was aimed at determining whether the cytokine exerts some effects on keratinocyte activation and can either enhance or antagonize interferon-gamma (IFN-gamma)-induced ICAM-1 or HLA-DR antigen expression. Using normal keratinocytes cultured in defined medium and cytofluorography, we showed that treatments of the human cells with the cytokine IL-4 alone had no effect on the induction of ICAM-1 or HLA-DR molecules. However, a transient, but significant enhanced expression of ICAM-1 was observed by the combination of IFN-gamma and IL-4 after 24 h of stimulation, which was followed by a reduction at 48 and 72 h. Conversely, IL-4, when added during the IFN-gamma activation stage, had no effect on MHC class II antigen expression of keratinocytes; however, the cytokine reduced the expression of these antigens when added 24 h before the stimulation by IFN-gamma. These results suggest that IFN-gamma and IL-4 may interact to regulate ICAM-1 and HLA-DR expression on keratinocytes.

Cellular adhesion antigen modulation in purpura pigmentosa chronica

BACKGROUND

Purpura pigmentosa chronica is an inflammatory skin disorder probably caused by an allergic reaction. Delayed-type hypersensitivity or immunocomplex vasculitis has been considered as a possible mechanism.

OBJECTIVE

Detailed analysis of cell adhesion molecule (CAM) modulation may give further insights into the pathogenesis and underlying immune reaction of this disease.

METHODS

By immunohistochemical techniques we investigated the in situ expression of integrins, selectins, and CAMs of the immunoglobulin superfamily.

RESULTS

Infiltrating lymphocytes expressed LFA-1, LFA-2, VLA-4, and VLA-5, whereas some of the macrophages were also positive for p150/95 and MAC-1. VLA-1 was found on lymphocytes near the basement membrane of the epidermis. Compared with uninvolved or healthy skin endothelial cells showed upregulation of ICAM-1, VCAM-1, and, focally, E-selectin. Some fibroblasts were positive for ICAM-1. ICAM-1 was also upregulated on lesional keratinocytes that also expressed alpha 2, alpha 3, and alpha 6 integrin chains on basal and suprabasal epidermal layers.

CONCLUSION

Our findings demonstrate characteristic modifications in the expression of CAMs in purpura pigmentosa chronica and indicate the involvement of the epidermis in this disease. This modulation shows close parallels to those described for chronic delayed-type immune reactions of the skin.

Circulating intercellular adhesion molecule-1 in amniotic fluid, maternal serum alpha-fetoprotein levels, and intrauterine growth retardation

OBJECTIVE

Our purpose was to determine if circulating intercellular adhesion molecule-1, a marker of chronic inflammation, is present in amniotic fluid in midtrimester, is increased in patients with elevated maternal serum alpha-fetoprotein level, and is associated with intrauterine growth retardation.

STUDY DESIGN

Amniotic fluid circulating intercellular adhesion molecule-1 levels were assayed by enzyme-linked immunoassay in 273 samples obtained by midtrimester amniocentesis in gestations involving a single, structurally normal fetus. The control group consisted of 108 patients with normal maternal serum alpha-fetoprotein levels and 165 patients with elevated levels. Intrauterine growth retardation was diagnosed if birth weight was < 10th percentile for the clinically estimated gestational age.

RESULTS

Circulating intercellular adhesion molecule-1 was detectable in amniotic fluid in 105 of 273 samples (38%). In the control group it was detectable in amniotic fluid in seven of 108 (6%). In patients with elevated maternal serum alpha-fetoprotein 97 of 164 (59%) had detectable levels (p < 0.001). Of the 273 cases 38 (14%) had intrauterine growth retardation. Of these 23 (59%) had detectable circulating intercellular adhesion molecule-1 levels (p < 0.001). Of the seven cases of intrauterine growth retardation with normal maternal serum alpha-fetoprotein levels, one (14%) had detectable circulating intercellular adhesion molecule-1. Of the 31 cases of intrauterine growth retardation with elevated maternal serum alpha-fetoprotein 22 (71%) had detectable circulating intercellular adhesion molecule-1. When circulating intercellular adhesion molecule-1 was detectable in amniotic fluid, increasing levels was significantly related to decreasing gestational age at delivery (p < 0.005).

CONCLUSIONS

Midtrimester amniotic fluid from normal pregnancies does not generally contain detectable circulating intercellular adhesion molecule-1. Detectable amniotic fluid levels are significantly related to a birth weight < 10th percentile at delivery and to elevated midtrimester maternal serum alpha-fetoprotein levels. Increasing circulating intercellular adhesion molecule-1 levels are related to shortened length of gestation. This test may contribute to risk assessment for intrauterine growth retardation and prematurity. Circulating intercellular adhesion molecule-1 is a known marker of inflammatory processes; its further study may also improve understanding of the pathophysiologic mechanisms of certain cases of intrauterine growth retardation and prematurity.

Changes in numbers of epidermal cell adhesion molecules caused by oral cyclosporin in psoriasis

AIM

To determine the effects of a three month course of low dose cyclosporin on the expression of epidermal cell adhesion molecules.

METHODS

Eighteen patients with psoriasis were treated for 12 weeks with either 2.5 or 5 mg/kg/day of oral cyclosporin. Biopsy specimens taken from skin before, during, and after cyclosporin treatment were stained immunohistochemically for CD 54 (ICAM-1), CD 29 (beta-1 integrins), and CD18 (beta-2 integrins).

RESULTS

There was a highly significant (p < 0.01) clinical response after 12 weeks of cyclosporin as assessed by the Psoriasis Area and Severity Index (PASI) score. The staining of CD 29 on keratinocytes of affected and unaffected psoriatic skin was not affected by cyclosporin. Epidermal CD54 was variably expressed in active psoriatic plaques and changed unpredictably after cyclosporin (p = NS). Staining for CD18 on large epidermal dendritic cells was reduced after cyclosporin (p < 0.02). The expression of CD18 by large epidermal dendritic cells during treatment correlated strongly with the PASI score at that time and one month after stopping cyclosporin (p < 0.02).

CONCLUSIONS

Persistence of epidermal staining for CD 54 in psoriasis is compatible with a good clinical response to cyclosporin. Residual staining for CD 18 on large epidermal dendritic cells may be a useful marker for early clinical relapse.

Melanocytes freshly isolated from normal human skin express the cell membrane receptor for the adhesive glycoprotein thrombospondin

Thrombospondin (TSP) is an adhesive protein with multiple binding sites, which is able to mediate several cell-to-cell and cell-to-matrix interactions, particularly through its cell membrane receptor (TSP-R). Because human keratinocytes are able to synthesize and express TSP, and as TSP is also localized at the dermal-epidermal junction in normal human skin, we questioned whether epidermal cells are able to bind available TSP, that is, to express TSP-R. To investigate this, we employed gold immunoelectron microscopy on epidermal cells freshly isolated from normal human skin; the TSP-R was detected by OKM5 monoclonal antibody. Epidermal cells showing ultrastructural characteristics of melanocytes were gold-stained on their plasma membrane, whereas keratinocytes, Langerhans cells and lymphocytes were unstained. Although functional studies are clearly necessary to clarify the role(s) played by the TSP-R on the cell surface of melanocytes, it is tempting to speculate that the TSP-R may be important for melanocyte adhesion to the dermal-epidermal junction and to keratinocytes. Such adhesion may not only subserve the steric localization of melanocytes, but also have important implications for those functional activities of melanocytes which have been shown to require close contact between these cells and adjacent keratinocytes and/or basement membrane components.

Expression of immune associated surface antigens of keratinocytes in human papillomavirus-derived lesions

The expression of immune associated surface antigens of keratinocytes was studied in human papillomavirus (HPV) derived lesions in order to determine whether HPV types have a regulatory role in the pathogenesis of papillomas. A series of cutaneous and mucosal lesions were immunolabeled with monoclonal antibodies to the major histocompatibility complex class 1 (beta 2-microglobulin) and 2 (HLA-DR antigens), intercellular adhesion molecule (ICAM-1) and glycoprotein CD36 (OKM5) as well as CD1a (Langerhans cells), CD4, CD8 (T cells) and CD11a (LFA1 antigen). Testing for the presence of HPV was carried out by in situ hybridization with biotinylated probes for viral DNA detection and typing. We observed a drastic reduction or a loss of beta 2-microglobulin by keratinocytes from cutaneous lesions in correlation with the disappearance of Langerhans cells. Only mild alterations were observed in mucosal lesions. HLA-DR expressed by keratinocytes was only detected in condylomas and laryngeal papillomas and was usually associated with a dense inflammatory reaction. This HLA-DR expression may be correlated with an up-regulation of ICAM-1 and the presence of LFA1 positive leukocytes, mainly of CD8 phenotype, in the epithelium. CD36 was detected on differentiated keratinocytes of all lesions; its expression seems related to the proliferation state of the lesions and probably does not represent an immune marker. The different reactivity patterns observed in cutaneous and mucosal lesions may reflect: 1. different roles for mucosal and cutaneous HPV types in the induction of immunoregulatory surface antigens of keratinocytes, or 2. the changing nature of the cytokines released by mononuclear cells and infected keratinocytes in these lesions.