Neuropeptides in psoriasis: an immunocytochemical and radioimmunoassay study

The present study examines the presence of neuropeptides in the skin and plasma of patients with psoriasis using the techniques of immunocytochemistry and radioimmunoassay. Immunocytochemistry failed to demonstrate differences in the pattern of neuropeptide innervation in psoriatic lesional skin when compared to normal skin. However, radioimmunoassay of skin biopsy extracts, both substance P and vasoactive intestinal polypeptide, were significantly elevated in psoriatic lesional skin when compared with both psoriatic non-lesional and normal control skin (p less than 0.001). There was no significant difference between the plasma levels of neuropeptides in psoriatic patients compared to those of control subjects, and no significant correlation among the plasma levels of neuropeptides with the surface area of involvement with psoriasis. The finding of elevated levels of substance P and vasoactive intestinal polypeptide in lesional psoriatic skin suggests that these peptides may be involved in the pathogenesis or maintenance of the psoriatic skin lesion and the development of safe and stable antagonists of these neuropeptides may have applications in the treatment of psoriasis.     

Very late antigen-1 in psoriasis: an immunohistochemical study

Background Currently, psoriasis is thought to be an inflammatory response to an antigenic stimulation, in which angiogenesis plays a fundamental role. Very late antigen‐1 (VLA‐1) is a β₁ integrin collagen receptor that is up‐regulated in many angiogenic processes. Data on its role in psoriasis are sparse. Objective In a prospective study, we evaluated the staining of VLA‐1 in lesional skin from patients with psoriasis and atopic dermatitis. Material and methods Frozen sections from skin biopsies of patients with chronic plaque‐type psoriasis (n = 18) and chronic atopic dermatitis (n = 7) were stained with a monoclonal antibody to VLA‐1. The number of blood vessels stained with VLA‐1 and the staining intensity were evaluated. These were correlated with the histologic features. Results The absolute number of blood vessels was found to be similar in the atopic and psoriatic samples. However, the number of vessels stained with anti‐VLA‐1, as well as the staining intensity, was shown to be significantly higher in the psoriasis group (P < 0.05). Differences between psoriatic lesions showing typical histological features of psoriasis and those showing features that overlap with dermatitis were found as well. Conclusions Expression of VLA‐1 was found significantly higher in lesional dermal blood vessels of psoriatic patients compared with atopic patients. These findings suggest a possible role for VLA‐1 in the pathological angiogenesis of psoriasis. It may be an additional tool for establishing the diagnosis of psoriasis and provide a basis for new strategies in the treatment of psoriasis.     

Cathepsin D expression in chronic plaque psoriasis: an immunohistochemical study

Cathepsins are lysosomal cysteine proteases, which are involved in a variety of physiologic processes such as proenzyme activation, antigen presentation, tissue remodeling, bone matrix resorption, and pathologic processes such as facilitating tumor invasion and modulating the process of programmed cell death. This study aimed to evaluate the pattern of cathepsin D (CD) expression in chronic plaque psoriasis in comparison to normal skin by means of immunohistochemistry. The study included 34 patients presenting with chronic plaque psoriasis and 10 age- and sex-matched normal subjects as control group. Sixty percent of normal skin showed granular positivity for CD confined to basal layer. CD is upregulated in psoaritic lesion with 94.1% positivity making a significant difference between psoriasis and normal skin as regards the percentage and distribution of CD expression, where the latter was predominantly diffuse in psoriatic lesion. The eight cases exposed to PUVA therapy showed reduction of CD positivity to 62.5% with a predominance of mild staining and focal expression compared to pretreatment biopsies. CD may have a role in the pathogenesis of psoriasis in view of its high percentage and diffuse expression in psoriatic epidermis. CD degradative capacity may be responsible for disordered differentiation and scale formation characteristic of psoriasis. Reduction of CD expression may be one of the pathways of PUVA mechanism of action.     

Superoxide dismutase in psoriasis, squamous cell carcinoma and basal cell epithelioma: an immunohistochemical study

Monoclonal antibodies against human Cu,Zn-superoxide dismutase (SOD) and Mn-SOD were used to stain frozen sections of normal and abnormal human skin. In normal human epidermis, the Cu,Zn-SOD antibody almost exclusively stained the basal cells. Mn-SOD antibody weakly stained the whole of the epidermis but more predominantly the basal cell layer. In psoriasis, Cu,Zn-SOD antibody mainly stained the basal cells of the lowest parts of the elongated rete ridges. Basal cells corresponding to the tip of the dermal papillae were weakly stained. Mn-SOD staining was considerably decreased in the psoriatic epidermis. In squamous cell carcinoma, staining with both Cu,Zn-SOD and Mn-SOD antibodies was decreased, and single cells positive for Cu,Zn-SOD were scattered throughout the tumour nests. In basal cell epithelioma, Cu,Zn-SOD staining was intense and diffusely distributed throughout the tumour nests, while Mn-SOD staining was absent.     

Heterogeneity of fluorescence in psoriasis after application of 5-aminolaevulinic acid: an immunohistochemical study

BACKGROUND: Psoriasis has been shown to highly accumulate protoporphyrin IX (PpIX), but a variable distribution within plaques after fluorescence diagnosis is seen. It is unknown what causes this heterogeneity of fluorescence in psoriatic skin, despite adequate keratolytic treatment. Variations in fluorescence might explain the variable and the mostly partial clinical response of psoriasis seen after photodynamic therapy (PDT). OBJECTIVES: This study examines morphological and immunohistochemical differences in inhomogeneous PpIX-induced fluorescence in stable plaque psoriasis. MATERIALS AND METHODS: Fourteen patients with stable plaque psoriasis were included in this study. In each patient one psoriatic plaque was incubated with 20% 5-aminolaevulinic acid (ALA) ointment for 3 h after keratolytic treatment. Fluorescence diagnosis with ALA-induced porphyrins (FDAP) was performed and subsequently high- and low-fluorescent psoriatic skin samples were biopsied. Biopsies were investigated with respect to histological hyperkeratosis (thickness of stratum corneum), proliferation (Ki-67 antigen), keratinization (K10, filaggrin) and inflammation (CD3). Digital images acquired with FDAP were analysed using image analysis software. RESULTS: Inhomogeneous fluorescence was seen in 12 of the 14 plaques. A significantly thicker stratum corneum was found in low-fluorescent psoriatic skin compared with highly fluorescent skin. Fluorescence intensity and thickness of the stratum corneum proved to be negatively correlated. The variable-fluorescent parts of the lesional psoriatic skin showed no differences in epidermal proliferation, keratinization or inflammation. CONCLUSIONS: Heterogeneous ALA-induced fluorescence in psoriasis plaques related to inhomogeneous distribution of PpIX in the epidermis may result from differences in penetration of ALA and/or light within a plaque caused by differences in stratum corneum thickness. The variable clinical response seen after PDT in psoriasis could be explained by this. These findings are consistent with the general assumption that optimal desquamation prior to FDAP or PDT is required for the most favourable results.     

Flexural versus plaque lesions in psoriasis: an immunohistochemical differentiation

Clinical presentation, therapeutic options, micro-environment and HLA-typing have been reported to be different in flexural psoriasis as compared to plaque psoriasis. We were interested in any difference concerning the pathogenesis of both conditions. By analysing T-cell subsets, NK-T cells and proliferation and differentiation markers, insight into the pathogenesis of both subtypes was obtained. Quantitative studies of T-cell subsets, cells expressing NK-receptors and markers of proliferation and differentiation in flexural and plaque psoriasis were investigated. Biopsies from 6 patients with both flexural and plaque lesions were obtained and processed for immunohistochemistry. Several T-cell subsets were stained: CD4+, CD8+, CD2+, CD25+, CD45RO+ and CD45RA+ T-cells. In addition cells expressing NK receptors were stained: CD94+ cells and CD161+ cells. T-cell subsets and cells expressing NK-receptors were analysed by immunohistochemical scoring. The proliferation marker Ki-67 and differentiation marker keratin-10 were revealed immunohistochemically by MIB-1 and RKSE60 respectively. Both markers were analysed using quantitative image analyses. The number of Ki-67 positive nuclei and the percentage of keratin-10 positive epidermal cells in flexural and plaque psoriasis were comparable. There is no difference between flexural and plaque psoriasis concerning other T-cell subsets. However a highly significant reduction is seen in flexural psoriasis with respect to CD161+ cells in the dermis. The similarity of chronic plaque psoriasis compared to flexural psoriasis with respect to T-cell subsets, epidermal proliferation and keratinization suggests that both conditions are pathogenetically identical. We propose the decreased quantity of lesional CD161+ cells in the dermis of flexural psoriatic lesions may result from chronic microbial challenge in flexural psoriasis.     

Oral retinoic acid metabolism blocking agent Rambazole for plaque psoriasis: an immunohistochemical study

BACKGROUND: The novel systemic all-trans retinoic acid metabolism blocking agent (RAMBA) R115866 (Rambazole(TM); Barrier Therapeutics, Geel, Belgium; further referred to as rambazole) increases intracellular levels of endogenous all-trans retinoic acid (RA). Well-known effects of RA are normalization of aberrant epithelial growth and differentiation. Hence, rambazole might be beneficial in the treatment of plaque psoriasis. OBJECTIVES: The dynamics of epidermal proliferation, keratinization, lesional T-cell subsets and cells expressing natural killer (NK)-receptors in plaque psoriasis were assessed during treatment with rambazole, as part of a phase IIa open-label clinical trial. METHODS: Six patients were treated with rambazole, 1 mg, once daily, for 8 weeks. At weeks 0, 2 and 8, psoriatic plaque severity scores (SUM) and biopsies from a target lesion were assessed. Epidermal proliferation (Ki67), keratinization markers (K10, K13, K19), T-cell subsets (CD3, CD4+, CD8+, CD45RO+, CD45RA+, CD2+, CD25+, GITR+) and cells expressing NK-receptors (CD94, CD161) were immunohistochemically stained and quantified with image analysis. RESULTS: At week 2 the mean SUM-score was virtually equal to baseline, which was accompanied immunohistochemically by equal epidermal hyperproliferation, a nonsignificant decrease in K10 positive epidermis and, overall, a nonsignificant increase in immunocyte subsets. At week 8, in contrast, plaque severity was reduced by 34% from baseline (P < 0.05). Improvements were also detected for epidermal proliferation (-63%; P < 0.01) and K10 expression (+29%; P < 0.01), compared with baseline. No induction of retinoid-specific keratinization (K13, K19) was observed. A nonsignificant reduction of all pathogenic T-cell subsets and cells expressing NK-receptors was observed at week 8 of treatment (P > 0.05). CONCLUSIONS: Clinical efficacy of rambazole is primarily the result of restoring proliferation (Ki67) and differentiation (K10) of epidermal keratinocytes. Secondly, relevant T-cell subsets and cells expressing NK-receptors showed nonsignificant reductions after 8 weeks of treatment with rambazole.     

Neuropeptide and neuronal marker studies in vitiligo

Neuropeptide and neuronal marker immunoreactivity was studied in skin biopsies from lesional and marginal areas in 12 patients with vitiligo, and in seven normal controls. The vitiligo was active in seven, static in two, and of unknown activity in three. Antibodies against general neuronal marker PGP 9.5 (PGP 9.5), substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal polypeptide (VIP), and neuropeptide Y (NPY), were used. The epidermis, dermo-epidermal junction, papillary and reticular dermis, and appendages, were assessed semiquantitatively for reactivity with each antibody. Staining with PGP 9.5 in the upper dermis was assessed quantitatively by image analysis. An increase in reactivity against NPY antibody was seen in five of 10 cases (three with active vitiligo) in the marginal areas, and in three of 12 subjects (all with active vitiligo) in the lesional vitiligo areas. VIP antibody reactivity showed a minimal increase in the marginal and lesional vitiligo areas (in two cases each, both of whom had active vitiligo), SP and CGRP reactivities did not differ from normal. PGP 9.5 staining was minimally increased at the dermo-epidermal junction and lower Malpighian layer in biopsies from marginal areas in three of 10 subjects (all with active vitiligo). Quantitative analysis of PGP 9.5 reactivity in the upper dermis showed no difference between vitiligo and normal biopsies. These findings support the concept of neuronal or neuropeptide involvement in vitiligo, and in particular suggest that NPY may have a role in the pathogenesis of the disease.     

Neuropeptides in skin disease: increased VIP in eczema and psoriasis but not axillary hyperhidrosis

The neuropeptides vasoactive intestinal polypeptide (VIP), substance P and somatostatin were studied in skin biopsies from patients with eczema, psoriasis and axillary hyperhidrosis. VIP concentrations were elevated in skin affected by eczema and psoriasis, whereas substance P and somatostatin levels did not differ from controls. There was a higher concentration of VIP, but not of substance P or somatostatin, in normal axillary skin when compared to adjacent trunk skin, with abundant VIP-containing fibres surrounding eccrine sweat glands. The VIP concentration was unchanged in skin affected by axillary hyperhidrosis. VIP may increase local blood flow in eczema and psoriasis, but does not appear to play a role in axillary hyperhidrosis.     

Mixed carcinoma in situ: an immunohistochemical study

A case of mixed carcinoma in situ , of the skin, is presented. The lesion, located on the right temple of a 71–year-old man, showed histologic features of Bowen's disease and cxtramammary Paget's disease. This case suggests that Bowen's disease and extramammary Paget's disease may arise from pluripotential adnexal epithelium capable of keratinocytic and glandular differentiation. Utilization of the peroxidase-antiperoxidase technique for demonstrating carcino-embryonic antigen was performed in order to identify the component interpreted as extramammary Paget's disease. This procedure is apparently more sensitive than the commonly employed histochcmical stains for demonstrating glandular differentiation.     

Vacuolated cells in neurofibroma: an immunohistochemical study

BACKGROUND: Vacuolated cells could be encountered in neurofibroma. OBJECTIVES: Frequency and immunohistochemical feature of vacuolated cells in neurofibroma. METHODS: Sixty-two lesions of neurofibroma including five plexiform neurofibromas were re-evaluated for the search of vacuolated cells. Immunohistochemical analysis was performed for cases with vacuolated cells. RESULTS: In five cases of plexiform neurofibroma and four cases of sporadic neurofibroma with endoneurial component, presence of vacuolated cells in the endoneurial mucoid area was noted. They were immunoreactive both with S-100 protein and CD34, mostly negative for factor XIIIa and negative for epithelial membrane antigen. Vacuolated cells were found neither in the diffuse portion of plexiform neurofibroma nor in sporadic diffuse neurofibroma. CONCLUSION: Presence of vacuolated cells is a highly characteristic feature of endoneurial portion of neurofibroma. Considering immunoreactivity both with S-100 protein and CD34 in the majority of vacuolated cells, they could be regarded as to represent endoneurial precursor cells in a certain stage of differentiation to Schwann cells.     

Monochromatic excimer light (308 nm): an immunohistochemical study of cutaneous T cells and apoptosis-related molecules in psoriasis

BACKGROUND: Various types of UVB radiation source (290-320 nm) are used in treating psoriasis and their therapeutic mechanism has been attributed to immunosuppressive properties. Recently, a new UVB source generated by a 308-nm excimer laser has been introduced for the treatment of psoriasis. OBJECTIVE: In this study we investigated the immunohistochemical evaluation of T cells and the expression of various apoptosis-related molecules in the psoriatic hyperproliferative skin before and after treatment with 308-nm monochromatic excimer light (MEL). METHODS: Ten patients (three women and seven men), ranging in age from 29 to 79 years, affected by plaque-type psoriasis vulgaris, were treated with MEL. Biopsies from psoriatic lesions of MEL-treated sites were taken before, 24 h and/or 48 h after the first irradiation and analysed by the immunophosphatase alkaline technique (APAAP). RESULTS: MEL treatment was found to cause a significant decrease in the rate of proliferation of keratinocytes and a relevant depletion of T cells in all psoriatic lesions, 48 h after the first irradiation: 308 nm light eliminated T cells from the psoriatic epidermis and also from the dermis, highlighting the ability of this UVB source to penetrate the skin compared with normal UVB and establish direct cytotoxic action on T cells infiltrating skin lesions. Rapid clearing of psoriatic lesions involves potential molecular targets of UVB in T cells including p53, which is upregulated after direct irradiation with 308-nm UVB. Moreover, Bcl-2 expression in healing psoriasis epidermis after MEL treatment is significantly decreased compared with untreated skin and the TUNEL (TdT-mediated dUTP-biotin nick end labelling) technique revealed the presence of relevant apoptotic keratinocytes in the irradiated epidermis. CONCLUSIONS: These results indicate that psoriatic skin after monochromatic excimer light therapy is associated with significant T-cell depletion and alterations of apoptosis-related molecules accompanied by a decreased proliferation index and clinical remission.