Differential expression of adhesion molecules on infiltrating cells in inflammatory dermatoses

Alpha1beta1 integrin is crucial for accumulation of epidermal T cells and the development of psoriasis

Psoriasis is a common T cell-mediated autoimmune inflammatory disease. We show that blocking the interaction of alpha1beta1 integrin (VLA-1) with collagen prevented accumulation of epidermal T cells and immunopathology of psoriasis. Alpha1beta1 integrin, a major collagen-binding surface receptor, was exclusively expressed by epidermal but not dermal T cells. Alpha1beta1-positive T cells showed characteristic surface markers of effector memory cells and contained high levels of interferon-gamma but not interleukin-4. Blockade of alpha1beta1 inhibited migration of T cells into the epidermis in a clinically relevant xenotransplantation model. This was paralleled by a complete inhibition of psoriasis development, comparable to that caused by tumor necrosis factor-alpha blockers. These results define a crucial role for alpha1beta1 in controlling the accumulation of epidermal type 1 polarized effector memory T cells in a common human immunopathology and provide the basis for new strategies in psoriasis treatment focusing on T cell-extracellular matrix interactions.

Lichen planus responding to efalizumab

Lichen planus (LP) is a common inflammatory skin disorder of unknown origin. When generalized and relapsing, treatment of LP can be a challenge. We present a patient with widespread and relapsing generalized LP who was treated with efalizumab for 3 months. Both pruritus and the skin lesions responded promptly to this biologic. In accordance with the previously reported efficacy in oral erosive LP, efalizumab may be a promising novel future treatment option for patients with cutaneous LP.

The role of very late antigen-1 in immune-mediated inflammation

The alpha1beta1 integrin, also known as "very late antigen" (VLA)-1, is normally expressed on mesenchymal cells, some epithelial cells, activated T cells, and macrophages, and interacts, via the I-domain of the extracellular domain of the alpha1 subunit, with collagen molecules in the extracellular matrix (ECM). By "outside-in" transmembranal signaling to the interior of the cell, it mediates adhesion, migration, proliferation, remodeling of the ECM, and cytokine secretion by endothelial cells, mesangial cells, fibroblasts, and immunocytes. Importantly, its expressions and functions are enhanced by inflammatory cytokines including interferon (IFN)gamma and tumor necrosis factor (TNF)alpha, thus augmenting angiogenesis and fibrosis linked, in particular, to inflammation. Moreover, within the immune system, VLA-1 marks effector memory CD4+ and CD8+ T cells that are retained in extralymphatic tissues by interactions of the integrin with collagen and produce high levels of IFNgamma. Thus, immune-mediated inflammation in vivo is inhibited by blockade of the VLA-1-collagen interaction in experimental animal models of arthritis, colitis, nephritis, and graft versus host disease (GVHD), suggesting that inhibiting the interaction of the alpha1 I-domain with its ligands or modulating "outside-in" signaling by VLA-1 would be a useful approach in the human diseases simulated by these experimental models.

The systemic immune response is more prominent than the mucosal immune response in the pathogenesis of periodontal disease

BACKGROUND/AIM

The diseased periodontium appears to express features of a systemic and a mucosal immune response. Our aims were to determine differences in immunoglobulin expression between gingivitis and periodontitis lesions and to ascertain whether immune and inflammatory cells were recruited into the diseased periodontium by the mucosal addressin adhesion molecule (MAdCAM-1).

METHODS

In situ hybridization and immunohistochemistry were used to detect the expression of chemokines, adhesion molecules and immunoglobulins in tissue sections of gingival and granulation tissues excised from periodontitis-affected sites and of healthy tissue and gingivitis-affected tissue excised during crown-lengthening procedures.

RESULTS

Greater numbers of plasma cells were observed in periodontitis gingival/granulation tissue lesions compared with gingivitis lesions. While IgA1 were predominant in all lesions, IgA2 and J-chain expressing plasma cells were present in increased proportions in gingival tissues compared with granulation tissue. Intracellular adhesion molecule-1 (ICAM-1) was higher in periodontitis than in gingivitis and interleukin-8 mRNA was higher in lesions with a pronounced neutrophil infiltrate. Vascular cell adhesion molecule-1 (VCAM-1) localized to the deep connective tissue and indicated the presence of a systemic type of immune response in this region. Periodontal tissues (n=71 biopsies) did not appear to express MAdCAM-1, in positive control sections of small intestine where it was detected.

CONCLUSION

Overall, the systemic-type immune response is predominant, and although the mucosal immune response is minor and limited to the superficial tissues it may have an important role in the host defense to periodontal pathogens.

The frequency of CLA+ CD8+ T cells in the blood of psoriasis patients correlates closely with the severity of their disease

Psoriasis is thought to be a T cell-mediated skin disease and the cutaneous lymphocyte antigen (CLA) is an important skin homing epitope for T cells. We have studied the relationship between disease severity (PASI) and phenotypic analysis of T cells in the blood of 36 patients with psoriasis focusing on the expression of CLA, VLA-4 and CD25 on CD4+ and CD8+ T cells. The patients had a higher frequency of circulating CLA+ CD8+ cells than healthy controls. Furthermore, a much stronger correlation was observed between PASI and the frequency of CLA+ CD8+ than CLA+ CD4+ T cells. The frequency of CLA+D8+ T cells correlated more strongly with redness, thickness and scaling of the skin lesions than the total affected body surface area. In contrast to CLA the T cell expression of VLA-4 did not demonstrate any such correlation. Finally, the expression of the activation marker CD25 on CD8+ T cells showed a strong correlation with disease severity in patients with moderate to severe psoriasis (PASI > 10) but such correlation was not observed for CD4+ T cells. These findings support the notion that circulating CLA+ CD8+ T cells may play an important role in the pathogenesis of psoriasis.

Overexpression of the oncofetal Fn variant containing the EDA splice-in segment in the dermal-epidermal junction of psoriatic uninvolved skin

The extracellular matrix protein, Fn, has critical functions in cell attachment, migration, differentiation, and proliferation. We have previously shown that fibronectin (Fn) is abnormally expressed and potentiates entry into the cell cycle of basal keratinocytes in uninvolved psoriatic skin, in combination with T cell lymphokines. It is not known what type of Fn is present in psoriatic skin, however, and how this Fn may regulate signaling. Embryonic forms of cellular Fn containing extra domains, designated EDA and EDB, are generated by alternative splicing and are seen in proliferating, developing tissue and in wound healing. Because the EDA segment enhances the integrin binding sequence Arg, Gly, Asp (RGD), which, when present, has been shown to be critical in integrin-extracellular matrix signaling, we were particularly interested in determining whether or not EDA-containing Fn (EDA+Fn) represented the aberrantly expressed Fn in psoriasis. Increased EDA+ Fn protein was demonstrated by immunostaining at the dermal-epidermal junction in clinically uninvolved skin from six of six patients with psoriasis, but not in skin from control subjects. Using reverse transcription polymerase chain reaction an increased ratio of EDA+ Fn versus EDA- Fn mRNA was present in epidermal samples from psoriatic but not control individuals. Interestingly, the EDA+Fn in the psoriatic epidermis had the IIICS region spliced out (EDA+, FDB-, IIICS-, III9+), which was shared with normal epidermis (EDA-, EDB-, IIICS-, III9+). These results suggest a selective predominance of the EDA+ Fn isoform at the dermal-epidermal junction of psoriatic skin. The consistent aberrant localization of EDA+ Fn at the dermal-epidermal junction in uninvolved skin of psoriatics may confer the hyperresponsiveness of psoriatic uninvolved basal keratinocytes for rapid cellular proliferation in response to T cell signals. Key words: immunohistochemistry/integrin/keratinocyte/RT-PCR.

Functional down-regulation of beta1 and beta2 integrins of lamina propria lymphocytes (LPL) and tumor-infiltrating lymphocytes (TIL) in colorectal cancer patients

Integrins play an important role in various lymphocyte functions. In this study, we isolated lamina propria lymphocytes (LPL) and tumor-infiltrating lymphocytes (TIL) from normal and malignant tissues in patients with colorectal cancer, and examined the expression of beta1 and beta2 integrins on these lymphocytes quantitatively with two-color flow cytometry. Both LPL and TIL expressed a lower level of common beta1 chain (CD29) in CD4 and CD8 subpopulations than did peripheral blood lymphocytes (PBL). Among the associated alpha chains, the expression levels of alpha1 (CD49a) and alpha2 (CD49b) were slightly higher, whereas those of alpha4 (CD49d) and alpha6 (CD49f) were markedly reduced in LPL and TIL. No significant differences were observed in expressions of any alpha1 integrin chains between these two lymphocytes populations. Similarly, both alphaL (CD11a) and beta2 (CD18) were down-regulated in TIL and LPL with CD8+ cytotoxic phenotype, but not in those with CD4+ phenotype. CD8+ TIL expressed a slightly but significantly higher level of alphaLbeta2 than did CD8+ LPL. CD8+ LPL and CD8+ TIL consistently showed significantly decreased binding to purified ICAM-1, VCAM-1 and HT29 colon cancer cells as compared with CD8+ PBL. Although CD8+ TIL showed a slightly higher level of adhesion to these substrates than did CD8+ LPL, the level was much lower than that in PBL. The expression pattern and functional down-regulation of these integrins may be one of the reasons why TIL cannot eradicate the cancer cells in colorectal cancer.

In vitro modulation of keratinocyte wound healing integrins by zinc, copper and manganese

Although the trace elements zinc, copper and manganese are used in vivo for their healing properties, their mechanism of action is still only partially known. Some integrins expressed by basal layer keratinocytes play an essential part in healing, notably alpha2beta1, alpha3beta1, alpha6beta4 and alphaVbeta5, whose expression and distribution in epidermis are modified during the re-epithelialization phase. This study demonstrates how the expression of these integrins are modulated in vitro by trace elements. Integrin expression was studied in proliferating keratinocytes in monolayer cultures and in reconstituted skin that included a differentiation state. After 48 h incubation with zinc gluconate (0.9, 1.8 and 3.6 microg/mL), copper gluconate (1, 2 and 4 microg/mL), manganese gluconate (0.5, 1 and 2 microg/mL) and control medium, integrin expression was evaluated by FACScan and immunohistochemistry. Induction of alpha2, alpha3, alphaV and alpha6 was produced by zinc gluconate 1.8 microg/mL in monolayers, of alpha2, alpha6 and beta1 by copper gluconate 2 and 4 microg/mL and of all the integrins studied except alpha3 by manganese gluconate 1 microg/mL. Thus, alpha6 expression was induced by all three trace elements. The inductive effect of zinc was particularly notable on integrins affecting cellular mobility in the proliferation phase of wound healing (alpha3, alpha6, alphaV) and that of copper on integrins expressed by suprabasally differentiated keratinocytes during the final healing phase (alpha2, beta1 and alpha6), while manganese had a mixed effect.

Update on oral lichen planus: etiopathogenesis and management

Lichen planus (LP) is a relatively common disorder of the stratified squamous epithelia, which is, in many ways, an enigma. This paper is the consensus outcome of a workshop held in Switzerland in 1995, involving a selection of clinicians and scientists with an interest in the condition and its management. The oral (OLP) eruptions usually have a distinct clinical morphology and characteristic distribution, but OLP may also present a confusing array of patterns and forms, and other disorders may clinically simulate OLP. Lesions may affect other mucosae and/or skin. Lichen planus is probably of multifactorial origin, sometimes induced by drugs or dental materials, often idiopathic, and with an immunopathogenesis involving T-cells in particular. The etiopathogenesis appears to be complex, with interactions between and among genetic, environmental, and lifestyle factors, but much has now been clarified about the mechanisms involved, and interesting new associations, such as with liver disease, have emerged. The management of lichen planus is still not totally satisfactory, and there is as yet no definitive treatment, but there have been advances in the control of the condition. There is no curative treatment available; immunomodulation, however, can control the condition. Based on the observed increased risk of malignant development, OLP patients should be offered regular follow-up examination from two to four times annually and asked to report any changes in their lesions and/or symptoms. Follow-up may be particularly important in patients with atrophic/ulcerative/erosive affections of the tongue, the gingiva, or the buccal mucosa. Much more research is required into the genetic and environmental aspects of lichen planus, into the premalignant potential, and into the possible associations with chronic liver, and other disorders. More clinical studies are required into the possible efficacy of immunomodulatory drugs such as pentoxifylline and thalidomide.

The CD11b/CD18-integrin in the pathogenesis of psoriasis

The aim of the present investigation was to study the distribution of CD11b, CD18, and ICAM-1 over the various cell populations present in the margin zone of the actively spreading psoriatic lesion and distant uninvolved psoriatic skin. This study was performed in order to obtain more insight in the relevance of these receptor molecules in the early phase of psoriatic plaque development. Skin biopsies were taken and inflammation markers were assessed using immunohistochemical techniques. All dermal changes in the margin zone preceded those in the epidermis. In the margin zone the most peripheral change was a decrease in dermal ICAM-1-expression, followed by an increase in dermal CD11b-expression. CD11b-positive cells showed a different tissue distribution from polymorphonuclear leukocytes and were more abundantly present, suggesting significant amounts of CD11b-bearing cell populations other than polymorphonuclear leukocytes in the early phase of psoriasis. Decreased numbers of CD18-positive cells in distant uninvolved skin suggest the existence of a selective modulating mechanism altering the trafficking of myeloid subpopulations. Polymorphonuclear leukocytes appeared to invade the skin well after the appearance of CD11b- and CD18-positive cells.

The regulation of CD11b integrin levels on human blood leukocytes and leukotriene B4-stimulated skin by a specific leukotriene B4 receptor antagonist (LY293111)

CD11b is part of the beta2-integrin Mac-1 and plays an important role in neutrophil adhesion. Leukotriene B4 (LTB4) is an active upregulator of neutrophil CD11b-expression, acts as a potent chemoattractant to neutrophils and is also known to upmodulate epidermal proliferation. We performed a placebo-controlled study on LY293111, an oral LTB4 receptor antagonist. Twenty healthy male volunteers were randomised over three treatment groups that received placebo, 48 mg, or 200 mg drug twice daily for 10 days. Before and after treatment, flow cytometrical CD11b assessment was performed on in vitro LTB4-stimulated peripheral blood neutrophils. Additionally, skin biopsies were taken at 24 and 72 h after epicutaneous LTB4 application, before and after treatment. The effects on skin were assessed immunohistochemically using various markers. All observed effects were dose related. CD11b upregulation on blood neutrophils was significantly suppressed in both treatment groups compared to placebo. In skin, a significant suppression of inflammation and hyperproliferation occurred. Pronounced inhibition was observed on neutrophil migration into the epidermis and the inflammatory infiltrate was decreased. A similar but weaker response was seen in the dermis. The number of cycling cells as well as suprabasal keratin-16 expression were decreased in both treatment groups. LY293111 proved to be a potent inhibitor of LTB4-induced cutaneous inflammation and hyperproliferation. The potent antiinflammatory effect in vivo and the fact that in the present study the compound showed no clinically significant side effects make it an interesting drug in the future treatment of inflammatory conditions predominated by neutrophils.

Immunologic aspects of dermal and oral lichen planus: a review

There have been many investigations, both experimental and epidemiologic, of the forms of LP affecting the skin and oral mucosae. These studies have provided a varied range of hypotheses to explain not only the factors determining susceptibility to and onset of this disease, but also the immunologic mechanisms leading to the pathosis with which LP is associated. Much progress has been made, especially through in vitro studies, regarding detailed aspects of the immunology of LP. However, data is often conflicting or incomplete. In this review we attempt to bring together the currently available data regarding the immunologic basis of LP.

Vla and alpha 6 beta 4 integrin expression in neuroendocrine carcinomas of the skin (their xenografts on nude mice and a corresponding primary culture)

Immunohistological expression of VLA1-5 and alpha 6 beta 4 integrins have been studied in 21 cases of primary neuroendocrine carcinomas of the skin (NECS), three xenografts on nude mice and one NECS cell culture. The phenotypic properties of NECS cells were largely maintained in NECS grafted on athymic nude-mice and in the corresponding cell line. Our results indicate that alpha 1 beta 1 and to a lesser extent alpha 3 beta 1, alpha 5 beta 1 are the main integrins expressed in NECS. In addition, VLA2, 4 and alpha 6 beta 4 are heterogeneously expressed in the same group of tumors and very sparsely present. These data suggest that like neuroblastoma and primitive peripheral neuroectodermal tumor (pPNET) the absence or the heterogeneous distribution of such integrins is correlated with the aggressive behaviour of NECS although long-term follow-up was not available for our cases. On the other hand, the alpha 1 expression could be regarded as a novel marker for differential diagnosis between NECS (alpha 1+) and pPNET (alpha 1-). The alpha 1 beta 1, alpha 2 beta 1, alpha 3 beta 1, alpha 5 beta 1 heterodimers in the 21 NECS studied showed an uniform pericellular staining of both the peripheral cells and central cells of the tumor islands. The predominant expression of alpha 1 beta 1 is consistent with the hypothesis of a primitive epithelial totipotential origin in NECS.

Expression of adhesion molecules and their ligands in contact allergy

Sequential biopsies from skin lesions induced by nickel sulphate and sodium lauryl sulphate, respectively, were investigated with respect to expression of extracellular matrix proteins and adhesion molecules on lymphocytes, endothelial cells, and keratinocytes. The majority of the infiltrating lymphocytes expressed VLA-4, LFA-1, CD44 and ICAM-1, a variable fraction expressed Leu-8 and VLA-5, and few or no cells were positive for VLA-1, VLA-2 and VLA-6. Noteworthy, was that the infiltrating cells showed a substantial amount of fibronectin but relatively small or negligible presence of laminin, collagen type IV, IgG, IgA, IgM, and albumin. The fibronectin was associated with cell bodies as well as the area surrounding infiltrating cells. The number of infiltrating cells was larger in biopsies from nickel-sulphate induced lesions and the infiltrates contained more fibronectin than biopsies from lesions induced by sodium lauryl sulphate. However, at the single-cell level, the expression of VLA antigens, LFA-1, CD44 and ICAM-1 was similar in both groups. The endothelial cells of skin biopsies from nickel-sulphate-induced lesions showed a stronger expression of VCAM-1, ELAM-1 and ICAM-1 compared to biopsies from sodium lauryl sulphate-induced lesions. In the biopsies from nickel sulphate-induced lesions, the keratinocytes showed a tendency to less VLA-6 expression. These results suggest that fibronectin plays a role in lymphocyte extravasation or extravascular lymphocyte migration.

Immunohistochemical localization of very late activation integrins in healthy and diseased human gingiva

The beta 1-integrins (VLA family) are cellular adhesion molecules (CAM) that play a major role in cell-cell and cell-matrix interactions. The expression pattern of CAM was studied in 5 clinically normal volunteers with healthy gingiva and in 18 patients with clinically different stages of periodontitis. In healthy human gingiva alpha 2, alpha 3 and alpha 6 integrin chains were found in a characteristic distribution, showing a broad continuous expression on the junctional and sulcular epithelium sites. The expression of these integrins was demonstrated primarily on the basal cell layers and in some cells of the stratum spinosum. Inflammatory stages of periodontitis revealed further upregulation of alpha 2, alpha 3 and alpha 6 integrins into the junctional and sulcular epithelial cells, which correlated with the stage of the periodontitis and the extent of the cellular infiltration. alpha 4 and alpha 6 were found to be the predominant beta 1 integrin chains on inflammatory cells. The amount of alpha 4 and alpha 6 positive infiltrative cells increased with the number of inflammatory cells. VCAM-1, the corresponding cell-cell ligand of VLA-4 (alpha 4) was present on the majority of subepithelial vessels in all stages of gingivitis and periodontitis. The alpha 5 subunit was expressed on both endothelium and gingival connective tissue cells. Samples from advanced periodontitis cases showed a higher number of alpha 5 positive mononuclear cells. In comparison to normal epidermis, human gingival epithelial cells express higher levels of integrins. This expression is further upregulated in advanced stages of periodontitis, indicating changes of the beta 1 integrin organization.

Pharmacologic modulation by cetirizine of some adhesion molecules expression in psoriatic skin lesions

BACKGROUND

Adhesion molecules play a major role in the pathogenesis of inflammatory skin diseases by regulating lymphocyte trafficking and homing in an inflamed area.

METHODS

The expression of the lymphocyte function-associated antigen-1 (LFA-1) and of its ligand, the intercellular adhesion molecule-1 (ICAM-1) has been studied in psoriatic skin lesions of 10 patients with guttate, nummular, and palmoplantar psoriasis. In addition, the peculiar immunophenotype of infiltrating cells (CD3, CD4, CD8, CD25) and their correlation with HLA-DR expression before and after treatment with oral cetirizine, a highly selective, third generation H1-receptor antagonist has been examined using the labeled avidin biotin (LAB) system.

RESULTS

Cetirizine treatment modulated in vivo the expression of adhesion molecules LFA-1/CAM-1 as shown in all cases by decreased levels of their expression on keratinocytes and on dermal endothelial cells (P < 0.001). The expression of HLA-DR on keratinocytes and endothelial cells was also inhibited after treatment. The numbers of infiltrating CD3-, CD4-, CD8-positive cells were reduced, whereas there was no significant modification of CD25-positive cells within the epidermis and the dermis.

CONCLUSION

This open clinical trial suggests that cetirizine could be effective in treating psoriasis: (1) for its symptomatic control on itching; (2) for its immunopharmacologic modulation of leukocyte integrins and on the immunophenotype pattern of infiltrating and resident cells, and (3) for contributing to the clearing of the lesions clinically.

Expression of integrin receptors and ICAM-1 on keratinocytes in vivo and in an in vitro reconstructed epidermis: effect of sodium dodecyl sulphate

Several integrin heterodimers such as alpha 2 beta 1, alpha 6 beta 4 and alpha v beta 5 are expressed on basal keratinocytes of the epidermis. Because overexpression of these integrins as well as induction of the intercellular adhesion molecule-1 (ICAM-1) have been found in inflammatory dermatoses, we sought to determine whether these modulations could be used as markers of skin irritation. In normal epidermis, topical application of 1% sodium dodecyl sulphate (SDS) for 24 h caused an upregulation of alpha 3, beta 1, alpha 6, beta 4, alpha v, beta 5 and to a lesser extent alpha 2 integrin chains as well as an induction of ICAM-1. To investigate whether these parameters could also be used for evaluation of skin irritancy in vitro, SDS was applied for 24 h to reconstructed epidermis on de-epidermized dermis (RE-DED). In RE-DED, integrin overexpression and aberrant alpha 5 expression was seen under normal in vitro culture conditions and topical application of SDS caused only marginal additional upregulation. We could not detect any ICAM-1 reactivity on either normal or irritated RE-DED. Our results demonstrate that the modulation of integrin and ICAM-1 expression can be used as markers of irritation of the epidermis in vivo, but not in vitro.

Investigation of epidermotropism in canine mycosis fungoides: expression of intercellular adhesion molecule-1 (ICAM-1) and beta-2 integrins

In human mycosis fungoides (MF), interactions between LFA-1 (CD11a/CD18) and ICAM-1 (CD54) are involved in lymphocyte adhesion to keratinocytes. The purpose of this study was to evaluate the expression of ICAM-1, beta-2 integrins and class II major histocompatibility complex molecules (MHC II) on keratinocytes and infiltrating lymphocytes in canine MF. Sections of frozen skin biopsy specimens from normal dogs (n = 3) and dogs with MF (n = 17) were evaluated by immunohistochemistry for expression of ICAM-1, beta-2 integrins, and class II MHC molecules. Our results demonstrated that in canine MF, ICAM-1 was expressed variably on epidermal and follicular keratinocytes. The extent of keratinocyte ICAM-1 expression did not correlate with the degree of lymphocyte epithelial infiltration, nor with lymphocyte LFA-1 expression. This was especially evident in cases of Pagetoid reticulosis-like disease in which prominent lymphocyte epidermotropism was not accompanied by keratinocyte ICAM-1 expression. Keratinocyte class II MHC molecule expression did not correlate with keratinocyte ICAM-1 expression. In conclusion, in canine MF, the lack of statistically significant correlations between epithelial lymphocyte infiltration and keratinocyte ICAM-1 expression, and between keratinocyte ICAM-1 and lymphocyte LFA-1 staining, suggests that the LFA-1/ICAM-1 pathway is not the major adhesion mechanism between lymphocytes and keratinocytes. It is suspected that different ligands of the LFA-1 integrin (e.g. ICAM-2) or other adhesion molecules (e.g. CD2/LFA-3, VLA-1) might be involved in the epitheliotropism phenomenon in canine MF. These hypothesis cannot be evaluated in the dog at this time owing to the lack of specific monoclonal antibodies.

VCAM-1 and ICAM-1 are expressed by Langerhans cells, macrophages and endothelial cells in oral lichen planus

Expression of intercellular adhesion molecule-1 (ICAM-1, CD54) and vascular cell adhesion molecule-1 (VCAM-1, CD106) was examined in oral lichen planus (OLP) and normal oral mucosa (NOM). Immunoperoxidase staining showed ICAM-1 expression by vascular endothelium in all biopsies of OLP and NOM whereas endothelial VCAM-1 staining was found in 2/7 NOM and 8/9 OLP. In the lamina propria of NOM occasional cells were ICAM-1 or VCAM-1 positive, and virtually no staining of intraepithelial dendritic cells was seen for either marker. Intraepithelial dendritic cells stained for ICAM-1 in 7/9 and VCAM-1 in 4/9 OLP biopsies. Double immunofluorescence showed dual labelling of Langerhans cells (LC) with CD1a and VCAM-1 in a further 5/12 cases of OLP, but there was no such staining in four NOM. This is the first report of LC staining with VCAM-1. Induction of ICAM-1 and VCAM-1 on LC and macrophages in OLP suggests these cells are activated and may contribute to the pathogenesis of OLP by presenting antigen to infiltrating lymphocytes.

Expression of integrins in human nail matrix

The aim of this study was to characterize cell-cell and cell-matrix interaction by evaluating the expression of different integrins in the nail matrix. Nail biopsies were obtained from two cadaver fingers, and eight patients with ingrowing toenails. Frozen sections were stained by indirect immunofluorescence using anti-alpha 1, anti-alpha 2, anti-alpha 3, anti-alpha 4, anti-alpha 5, anti-alpha 6, anti-alpha v, anti-beta 1, anti-beta 4 and anti-ICAM-1 monoclonal antibodies. Biopsies from normal human foreskin were evaluated as controls. alpha 1, alpha 4 and alpha 5 subunits were absent from both nail matrix and normal human skin. alpha 2, alpha 3 and beta 1 subunits were expressed in the basal and suprabasal layers of nail matrix, but only in the basal layer of skin epidermis. alpha 6 and beta 4 subunits were strongly expressed in the basement membrane zone and in the basal layer of both nail matrix and epidermis. The alpha v subunit was expressed in the basal layer of nail matrix. ICAM-1 was not expressed in nail matrix epidermis. Our findings show that despite the distinctive features of the nail apparatus, compared with the epidermis, the pattern of integrin expression is similar, although some differences in the distribution of alpha 2, alpha 3 and beta 1 subunits are detectable. These are probably related to the peculiar differentiation and keratinization of the nail.

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.

Immunophenotypic analysis suggests that granuloma faciale is a gamma-interferon-mediated process

Granuloma faciale (GF) is an uncommon inflammatory dermatosis with characteristic clinical and histologic features. Very little is known about its pathogenesis. We used a battery of immunoperoxidase lymphocyte markers to study the population of hematopoietic cells present in a case of GF. The majority of non-myelocytic hematopoietic cells present were T-helper lymphocytes. The cells stained strongly with antibodies against the interleukin-2 receptor and with anti-lymphocyte functional antigen (LFA 1 alpha) antibodies. Overlying keratinocytes did not stain with ICAM-1 or HLA-DR, which may account for the presence of the Grenz zone in granuloma faciale. These findings suggest that a gamma-interferon-mediated process may play some role in the pathogenesis of this disorder.