Relevance of compartmentalization of T-cell subsets for clinical improvement in psoriasis: effect of immune-targeted antipsoriatic therapies.

BACKGROUND: Therapies targeting the T cell-mediated pathology of psoriasis have been found to achieve remarkable clinical improvement and have confirmed the crucial role of the immune system either in peripheral blood (PB) or in skin. No analyses of T-cell counts in both compartments have been conducted in order to confirm or refute the hypothesized shifts between them. OBJECTIVES: To gain more insight in the dynamics of compartmentalization of T cells between PB and lesional skin of patients with psoriasis, in response to immune-targeted antipsoriatic therapies. METHODS: Eighteen patients with psoriasis received either efalizumab (n = 9) or etanercept (n = 9) for 12 weeks. Biopsies were taken for immunohistochemical analysis of T-cell subsets and simultaneously T-cell subsets were isolated from PB specimens by flow cytometry. RESULTS: The Psoriasis Area and Severity Index declined significantly after 12 weeks of etanercept, but not for efalizumab. After treatment with efalizumab, a significantly decreased number of all T-cell subsets was found in the dermis. In the epidermis, CD4+, CD8+, CD25+, CD45RO+ and CD161+ T-cell subsets were significantly decreased. With respect to etanercept, few significant changes in T-cell subsets were found. The percentage of lymphocytes in PB was significantly elevated after efalizumab treatment regardless of responder status. CONCLUSIONS: Treatment with efalizumab establishes successful recompartmentalization of T-cell subsets with modest clinical efficacy after 12 weeks, whereas in etanercept-treated patients, a significant clinical response is no guarantee for significant changes in T-cell subsets in the different compartments. Reductions in T-cell subsets cannot be used as predictive markers for the clinical response to therapy. Interference with the studied T-cell populations in its own right seems not to be responsible for the clinical efficacy of efalizumab and etanercept.

CD26/dipeptidyl-peptidase IV in psoriatic skin: upregulation and topographical changes.

BACKGROUND: Psoriasis is known to affect 2-3% of the population and can be considered an organ-specific autoimmune disease. CD26/dipeptidyl-peptidase IV (DPP-IV) is a membrane-bound protease with diverse properties. In theory, the expression of CD26/DPP-IV has common grounds with three principal key players of the psoriatic pathogenesis: keratinocytes, T cells and cytokines. OBJECTIVES: To assess CD26/DPP-IV expression in psoriasis in order to expand on the search for complementary biomarkers related to inflammation and proliferation in psoriasis. METHODS: The pattern of expression of CD26/DPP-IV was investigated on the mRNA-, protein- and enzyme-functionality level using immunohistochemical, immunofluorescent and enzyme activity labelling techniques. RESULTS: An 11-fold significant increase of CD26/DPP-IV on the mRNA level was demonstrated in psoriatic epidermal sheets compared with normal skin. Immunohistochemistry on psoriatic sections showed a distinct patchy honeycomb-like CD26/DPP-IV staining in the suprapapillary layers. Moreover, a clearly distinguishable column-like staining pattern throughout the suprabasal compartment along the rete ridges was seen, whereas in normal skin these patterns were absent. Strikingly, CD26/DPP-IV enzyme activity correlated with this immunohistochemical reactivity pattern for the CD26/DPP-IV protein. The T-cell bound expression of CD26/DPP-IV in psoriatic skin was explicitly present, albeit in small quantities. CONCLUSIONS: Our data provide clear evidence for a versatile upregulation of CD26/DPP-IV expression in psoriatic (epi)dermis. Although the exact functional contribution remains speculative, the topographical distribution of this complex multifunctional protein suggests a suitable role as a complementary biomarker in psoriasis.

A double-blind, randomized quantitative comparison of calcitriol ointment and calcipotriol ointment on epidermal cell populations, proliferation and differentiation.

BACKGROUND: Calcitriol and calcipotriol are widely used in the topical treatment of psoriasis. However, studies comparing both treatment modalities are scarce. Especially, there are almost no studies comparing the effects on epidermal cell populations in a quantitative manner. OBJECTIVES: The aim of this study was to quantitatively compare the effects of topical calcitriol and topical calcipotriol on clinical scores and epidermal subpopulations. PATIENTS AND METHODS: From five patients with stable plaque psoriasis, skin biopsies were taken from two symmetrical regions on the trunk or extremities before and after treatment with either calcitriol or calcipotriol. Frozen sections were labelled immunofluorescently using direct immunofluorescence for beta-1 integrin and the Zenon labelling technique for keratin (K) 6, K10 and K15. The digital photographs of the stained sections were quantitatively analysed and the results of both treatments were compared. RESULTS: The clinical SUM-score improved significantly for both the calcitriol- and the calcipotriol-treated lesions. In the calcipotriol-treated group the expression of K10 and K15 increased and the expression of K6 decreased significantly. No changes were seen for the marker beta-1 integrin. In the calcitriol-treated group none of the markers changed significantly. A tendency towards significance was seen for the changes in the expression of K6 and K15 in favour of calcipotriol. CONCLUSIONS: Both calcitriol and calcipotriol gave a significant improvement in clinical scores. However, treatment with calcipotriol resulted in a normalization of K6, K10 and K15, whereas treatment with calcitriol did not. Comparison of both treatments showed a tendency towards significance for the above-mentioned markers for calcipotriol only.

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.

Explorative immunohistochemical study to evaluate the addition of a topical corticosteroid in the early phase of alefacept treatment for psoriasis.

The aim of this study was to explore the additional effect of betamethasone dipropionate cream in the early phase of an intramuscular (IM) alefacept course, on plaque severity and on modulating T-cell subsets, cells expressing NK-receptors, epidermal proliferation and keratinocyte differentiation in lesional psoriatic skin. Therefore, sixteen patients with moderate-to-severe chronic plaque psoriasis received 15 mg alefacept IM for 12 weeks, followed by a 12-week follow-up period. The first 4 weeks, patients were randomized 1:1 to either betamethasone dipropionate, or the vehicle cream, once daily. Plaque severity (SUM) was assessed and serial biopsies were immunohistochemically stained for T-cell subsets (CD3, CD4, CD8, CD45RO, CD45RA, CD2, CD25, GITR), cells expressing NK-receptors (CD94 and CD161), epidermal proliferation (Ki67) and differentiation (K10), which were quantified using manual and digital image analysis. Alefacept monotherapy resulted in statistically significant improvement in plaque severity. Subsequently, immunohistochemical assessments on T-cell subsets, epidermal proliferation (Ki67) and keratinization (K10) revealed marked time-related improvements with respect to the mentioned parameters, without significant differences between both treatment regimens. Alefacept monotherapy induces improvement of plaque severity, which is accompanied by a reduction in activated (CD2+, CD25+, CD45RO+) dermal CD4+ and activated epidermal CD8+ T cells, epidermal proliferation and differentiation. Once daily treatment with betamethasone dipropionate cream during the first 4 weeks of an intramuscular alefacept course did not provide substantial additional clinical and immunohistochemical improvement.