Defining trajectories of response in patients with psoriasis treated with biologic therapies

BACKGROUND

The effectiveness and cost-effectiveness of biologic therapies for psoriasis are significantly compromised by variable treatment responses. Thus, more precise management of psoriasis is needed.

OBJECTIVES

To identify subgroups of patients with psoriasis treated with biologic therapies, based on changes in their disease activity over time, that may better inform patient management.

METHODS

We applied latent class mixed modelling to identify trajectory-based patient subgroups from longitudinal, routine clinical data on disease severity, as measured by the Psoriasis Area and Severity Index (PASI), from 3546 patients in the British Association of Dermatologists Biologics and Immunomodulators Register, as well as in an independent cohort of 2889 patients pooled across four clinical trials.

RESULTS

We discovered four discrete classes of global response trajectories, each characterized in terms of time to response, size of effect and relapse. Each class was associated with differing clinical characteristics, e.g. body mass index, baseline PASI and prevalence of different manifestations. The results were verified in a second cohort of clinical trial participants, where similar trajectories following the initiation of biologic therapy were identified. Further, we found differential associations of the genetic marker HLA-C*06:02 between our registry-identified trajectories.

CONCLUSIONS

These subgroups, defined by change in disease over time, may be indicative of distinct endotypes driven by different biological mechanisms and may help inform the management of patients with psoriasis. Future work will aim to further delineate these mechanisms by extensively characterizing the subgroups with additional molecular and pharmacological data.

Psoriasis treat to target: defining outcomes in psoriasis using data from a real-world, population-based cohort study (the British Association of Dermatologists Biologics and Immunomodulators Register, BADBIR)

Background

The ‘treat to target’ paradigm improves outcomes and reduces costs in chronic disease management but is not yet established in psoriasis.

Objectives

To identify treatment targets in psoriasis using two common measures of disease activity: Psoriasis Area and Severity Index (PASI) and Physician's Global Assessment (PGA).

Methods

Data from a multicentre longitudinal U.K. cohort of patients with psoriasis receiving systemic or biologic therapies (British Association of Dermatologists Biologics and Immunomodulators Register, BADBIR) were used to identify absolute PASI thresholds for 90% (PASI 90) and 75% (PASI 75) improvements in baseline disease activity, using receiver operating characteristic curves. The relationship between PGA (clear, almost clear, mild, moderate, moderate–severe, severe) and PASI (range 0–72) was described, and the concordance between absolute and relative definitions of response was determined. The same approach was used to establish treatment response and eligibility definitions based on PGA.

Results

Data from 13 422 patients were available (58% male, 91% white ethnicity, mean age 44·9 years), including over 23 000 longitudinal PASI and PGA scores. An absolute PASI ≤ 2 was concordant with PASI 90 and an absolute PASI ≤ 4 was concordant with PASI 75 in 90% and 88% of cases, respectively. These findings were robust to subgroups of timing of assessment, baseline disease severity and treatment modality. PASI and PGA were strongly correlated (Spearman's rank correlation coefficient 0·92). The median PASI increased from 0 (interquartile range 0–0, range 0–23) to 19 (interquartile range 15–25, range 0–64) for PGA clear to severe, respectively. PGA clear/almost clear was concordant with PASI ≤ 2 in 90% of cases, and PGA moderate–severe severe was concordant with the National Institute for Health and Care Excellence PASI eligibility criteria for biologics in 81% of cases.

Conclusions

An absolute PASI ≤ 2 and PGA clear/almost clear represent relevant disease end points to inform treat‐to‐target management strategies in psoriasis.

What's already known about this topic?

The most commonly used relative disease activity measure in psoriasis is ≥ 90% improvement in Psoriasis Area and Severity Index (PASI 90); however, it has several limitations including dependency on a baseline severity assessment.

Defining an absolute target disease activity end point in psoriasis has the potential to improve patient outcomes and reduce costs, as demonstrated by treat‐to‐target approaches in other chronic diseases such as hypertension and diabetes.

The Physician's Global Assessment (PGA) is a popular alternative measure of psoriasis severity in daily practice; however, its utility has not been formally assessed with respect to PASI.

What does this study add?

An absolute PASI ≤ 2 corresponds with PASI 90 response and is a relevant disease end point for treat‐to‐target approaches in psoriasis.

There is a strong correlation between PASI and PGA.

PGA moderate–severe/severe may serve as an alternative eligibility criterion for biologics to PASI‐based definitions, and PGA clear/almost clear is an appropriate alternative absolute treatment end point.

What are the clinical implications of this work?

Absolute PASI ≤ 2 and PGA clear/almost clear represent relevant disease end points to inform treat‐to‐target management strategies in psoriasis.

Linked Editorial: Takeshita. Br J Dermatol 2020; 182:1075–1076.

Does weight loss reduce the severity and incidence of psoriasis or psoriatic arthritis? A Critically Appraised Topic

CLINICAL QUESTION

Does weight loss reduce the severity and incidence of psoriasis or psoriatic arthritis (PsA) in obese individuals?

BACKGROUND

Obesity presents a rising public health challenge and is more prevalent among individuals with psoriasis or PsA than in the general population. Longitudinal population-based studies suggest a causal role for obesity in psoriasis and PsA onset and that obesity drives greater disease severity.

METHODS

We systematically reviewed evidence within the MEDLINE, Embase and CENTRAL databases and clinical trials registries examining lifestyle, pharmacological and surgical weight loss interventions in the treatment and prevention of psoriasis and PsA in obese individuals. Meta-analysis was conducted using random-effects models, followed by sensitivity analyses.

RESULTS

Of 176 full-text articles reviewed, 14 met the inclusion criteria. Meta-analysis of six randomized control trials (RCTs) confirmed that weight loss following lifestyle interventions (diet or physical activity) improves psoriasis compared with control [mean change in Psoriasis Area and Severity Index -2·59, 95% confidence interval (CI) -4·09 to -1·09; P < 0·001]. One RCT demonstrated a greater likelihood of achieving minimal PsA activity following diet-induced weight loss (odds ratio 4·20, 95% CI 1·82-9·66; P < 0·001). Three studies of pharmacological treatments reported conflicting results, and no RCTs of bariatric surgery were identified. Two cohort studies suggested that bariatric surgery, particularly gastric bypass, reduces the risk of developing psoriasis (hazard ratio 0·52, 95% CI 0·33-0·81; P < 0·01).

CONCLUSIONS

These limited data indicate that weight loss can improve pre-existing psoriasis and PsA, and prevent the onset of psoriasis in obese individuals. Together with the National Institute for Health and Care Excellence obesity guidance, this informed a local obesity screening and management pathway, providing multidisciplinary weight loss interventions alongside conventional skin-focused care for patients with psoriasis.

Spatial constraints govern competition of mutant clones in human epidermis

Deep sequencing can detect somatic DNA mutations in tissues permitting inference of clonal relationships. This has been applied to human epidermis, where sun exposure leads to the accumulation of mutations and an increased risk of skin cancer. However, previous studies have yielded conflicting conclusions about the relative importance of positive selection and neutral drift in clonal evolution. Here, we sequenced larger areas of skin than previously, focusing on cancer-prone skin spanning five decades of life. The mutant clones identified were too large to be accounted for solely by neutral drift. Rather, using mathematical modelling and computational lattice-based simulations, we show that observed clone size distributions can be explained by a combination of neutral drift and stochastic nucleation of mutations at the boundary of expanding mutant clones that have a competitive advantage. These findings demonstrate that spatial context and cell competition cooperate to determine the fate of a mutant stem cell.

Deep sequencing technologies allow for the investigation of clonal evolution in human cancers. Here the authors, combining sequencing data from human skin with mathematical modelling and simulations, suggest that the spatial context of a mutation with respect to other mutant clones may lead to differential clonal evolution.

European consensus statement on phenotypes of pustular psoriasis

Pustular psoriasis (PP) is a group of inflammatory skin conditions characterized by infiltration of neutrophil granulocytes in the epidermis to such an extent that clinically visible sterile pustules develop. Because of clinical co-incidence, PP is currently grouped with psoriasis vulgaris (PV). However, PP and PV are phenotypically different, respond differently to treatments and seem to be distinct on the genetic level. In contrast to PV, the phenotypes of PP are not well defined. Descriptions of each form of PP are discordant among standard dermatology textbooks [Saurat Dermatologie 2016, Rook's Dermatology 2016, Fitzpatrick's 2012 and Braun-Falco 2012], encumbering the collection of phenotypically well-matched groups of patients as well as clinical trials. The European Rare and Severe Psoriasis Expert Network (ERASPEN) was founded to define consensus criteria for diagnosis, deeply phenotype large groups of PP patients, analyse the genetics and pathophysiology and prepare for prospective clinical trials. This work reviews historical aspects of these conditions, new genetic findings and presents our initial considerations on the phenotypes of PP and a consensus classification of clinical phenotypes that will be used as a baseline for further, prospective studies of PP. Generalized pustular psoriasis (GPP) is defined as primary, sterile, macroscopically visible pustules on non-acral skin (excluding cases where pustulation is restricted to psoriatic plaques). GPP can occur with or without systemic inflammation, with or without PV and can either be a relapsing (>1 episode) or persistent (>3 months) condition. Acrodermatitis continua of Hallopeau (ACH) is characterized by primary, persistent (>3 months), sterile, macroscopically visible pustules affecting the nail apparatus. Palmoplantar pustulosis (PPP) has primary, persistent (>3 months), sterile, macroscopically visible pustules on palms and/or soles and can occur with or without PV.

IL-12-secreting CD19-targeted cord blood-derived T cells for the immunotherapy of B-cell acute lymphoblastic leukemia

Disease relapse or progression is a major cause of death following umbilical cord blood (UCB) transplantation (UCBT) in patients with high-risk, relapsed or refractory acute lymphoblastic leukemia (ALL). Adoptive transfer of donor-derived T cells modified to express a tumor-targeted chimeric antigen receptor (CAR) may eradicate persistent disease after transplantation. Such therapy has not been available to UCBT recipients, however, due to the low numbers of available UCB T cells and the limited capacity for ex vivo expansion of cytolytic cells. We have developed a novel strategy to expand UCB T cells to clinically relevant numbers in the context of exogenous cytokines. UCB-derived T cells cultured with interleukin (IL)-12 and IL-15 generated >150-fold expansion with a unique central memory/effector phenotype. Moreover, UCB T cells were modified to both express the CD19-specific CAR, 1928z, and secrete IL-12. 1928z/IL-12 UCB T cells retained a central memory-effector phenotype and had increased antitumor efficacy in vitro. Furthermore, adoptive transfer of 1928z/IL-12 UCB T cells resulted in significantly enhanced survival of CD19(+) tumor-bearing SCID-Beige mice. Clinical translation of CAR-modified UCB T cells could augment the graft-versus-leukemia effect after UCBT and thus further improve disease-free survival of transplant patients with B-cell ALL.

Predicting treatment response in psoriasis using serum levels of adalimumab and etanercept: a single-centre, cohort study

BACKGROUND

A substantial proportion of patients with psoriasis do not respond, or lose initial response to tumour necrosis factor-α antagonists. One possible mechanism relates to subtherapeutic drug levels due to an immunogenic antibody response.

OBJECTIVES

To investigate the association between serum adalimumab and etanercept levels, antidrug antibody levels and clinical response in a cohort of patients with psoriasis using a commercially available enzyme-linked immunoassay.

METHODS

In a single-centre cohort of 56 adults with chronic plaque psoriasis initiated on adalimumab or etanercept monotherapy between 2009 and 2011, drug and antidrug antibody levels were measured at the patients' routine clinic reviews (4, 12 and 24 weeks of treatment and the last available observation). Patients' responses at 6 months were stratified into responders [75% reduction in Psoriasis Area and Severity Index from baseline (PASI 75) or Physician's Global Assessment score of 'clear' or 'nearly clear'] and nonresponders (failure to achieve PASI 50).

RESULTS

After 4 weeks, adalimumab levels were significantly higher in responders compared with nonresponders (P = 0·003) and these higher levels were sustained at 12 and 24 weeks. Anti adalimumab antibodies were detected in 25% of nonresponders (two of eight patients, average 22·5 weeks' follow-up) and none of the responders (n = 23, average 26·1 weeks' follow-up). There was no significant association between etanercept levels and clinical response at 4 weeks (P = 0·317) and no antietanercept antibodies were detected. Lack of serum trough levels may have resulted in underestimation of the prevalence of antidrug antibodies.

CONCLUSIONS

Early adalimumab drug level monitoring at 4 weeks may be useful in predicting treatment response and potentially reduce drug exposure (and associated cost) with earlier review of treatment in those with low levels. No conclusions about the value of etanercept drug monitoring can be made due to the paucity of data. Larger studies are now required to assess the clinical utility and cost-effectiveness of these assays in personalizing therapy in psoriasis.

Graft-versus-host disease after double-unit cord blood transplantation has unique features and an association with engrafting unit-to-recipient HLA match

Manifestations of and risk factors for graft-versus-host disease (GVHD) after double-unit cord blood transplantation (DCBT) are not firmly established. We evaluated 115 DCBT recipients (median age, 37 years) who underwent transplantation for hematologic malignancies with myeloablative or nonmyeloablative conditioning and calcineurin inhibitor/mycophenolate mofetil immunosuppression. Incidence of day 180 grades II to IV and III to IV acute GVHD (aGVHD) were 53% (95% confidence interval, 44 to 62) and 23% (95% confidence interval, 15 to 31), respectively, with a median onset of 40 days (range, 14 to 169). Eighty percent of patients with grades II to IV aGVHD had gut involvement, and 79% and 85% had day 28 treatment responses to systemic corticosteroids or budesonide, respectively. Of 89 engrafted patients cancer-free at day 100, 54% subsequently had active GVHD, with 79% of those affected having persistent or recurrent aGVHD or overlap syndrome. Late GVHD in the form of classic chronic GVHD was uncommon. Notably, grades III to IV aGVHD incidence was lower if the engrafting unit human leukocyte antigen (HLA)-A, -B, -DRB1 allele match was >4/6 to the recipient (hazard ratio, 0.385; P = .031), whereas engrafting unit infused nucleated cell dose and unit-to-unit HLA match were not significant. GVHD after DCBT was common in our study, predominantly affected the gut, and had a high therapy response, and late GVHD frequently had acute features. Our findings support the consideration of HLA- A,-B,-DRB1 allele donor-recipient (but not unit-unit) HLA match in unit selection, a practice change in the field. Moreover, new prophylaxis strategies that target the gastrointestinal tract are needed.

Psoriasis is associated with pleiotropic susceptibility loci identified in type II diabetes and Crohn disease

BACKGROUND

Psoriasis is an immune-mediated skin disorder that is inherited as a multifactorial trait. Linkage analyses have clearly mapped a primary disease susceptibility locus to the major histocompatibility complex (MHC) region on chromosome 6p21. More recently, whole-genome association studies have identified two non-MHC disease genes (IL12B and IL23R), both of which also confer susceptibility to Crohn disease (CD).

OBJECTIVE AND METHODS

To ascertain the genetic overlap between these two inflammatory conditions further, we investigated 15 CD-associated loci in a psoriasis case-control dataset.

RESULTS

The analysis of 1256 patients and 2938 unrelated controls found significant associations for loci mapping to chromosomes 1q24 (rs12035082, p = 0.009), 6p22 (rs6908425, p = 0.00015) and 21q22 (rs2836754, p = 0.0003). Notably, the marker showing the strongest phenotypic effect (rs6908425) maps to CDKAL1, a gene also associated with type 2 diabetes.

CONCLUSIONS

These results substantiate emerging evidence for a pleiotropic role for s genes that contribute to the pathogenesis of immune-mediated disorders.

Fludarabine vs cladribine plus busulfan and low-dose TBI as reduced intensity conditioning for allogeneic hematopoietic stem cell transplantation: a prospective randomized trial

Purine analogs are often used for conditioning preceding allogeneic hematopoietic stem cell transplantation (HCT). We prospectively tested fludarabine (Flu) 40 mg/m(2)/day x 5 days vs cladribine (Clad) 10 mg/m(2)/day x 5 days plus oral busulfan (1 mg/kg q6 h x 2 days) and total body irradiation 200 cGy in 32 recipients of matched sibling and unrelated donor (URD) HCT. Patients were similar in age (median 52 years), diagnosis, extensive pre-HCT therapy (56 vs 63%), and high-risk disease status (81 vs 93%). Neutrophil engraftment was prompt (median 11 vs 12 days), but early graft failure using Clad halted randomization. Platelet recovery was prompt (median Flu 18 vs Clad 24 days). Graft-versus-host disease (GVHD) after Flu vs Clad was similar; (acute grade II/IV 56 vs 69%, P=0.26; chronic 50 vs 31%, P=0.27). Nonrelapse mortality (Flu 25 vs Clad 38%, P=0.47) and progression-free survival at 3 years were similar as well. Multivariate analyses showed slightly, but not significantly lower relative risk (RR) of neutrophil engraftment with Clad (RR 0.6 (95% CI 0.2-1.3) P=0.16) and with URD RR 0.4 (0.2-1.0) P=0.04). Older patients with advanced hematologic malignancies achieve satisfactory outcomes using either of these reduced intensity conditioning regimens.

Low incidence of Epstein-Barr virus-associated posttransplantation lymphoproliferative disorders in 272 unrelated-donor umbilical cord blood transplant recipients

Umbilical cord blood (UCB) is being increasingly used for transplantation, but the ability of neonatal T cells to regulate Epstein-Barr virus (EBV)-associated lymphoproliferation is unknown. Because UCB transplantation (UCBT) is associated with a relatively low infused dose of donor T cells, frequent donor-recipient HLA disparity, and use of antithymocyte globulin during conditioning, we hypothesized that the risk of EBV-associated posttransplantation lymphoproliferative disorders (EVB-PTLD) after UCBT may be increased. To investigate the incidence of EBV-PTLD after UCBT, we analyzed 272 unrelated-donor UCBTs performed from August 1993 to December 1999 at Duke University Medical Center and the University of Minnesota. Five cases of EBV-PTLD were identified, with a cumulative incidence of 2% (95% confidence interval, 0.3%-3.7%) at 2 years. EBV-PTLD affected UCB recipients aged 1 to 49 years (median, 8 years), with 4 patients undergoing transplantation for leukemia and 1 for immunodeficiency. Patients received UCB grafts that were HLA matched (n = 1) or mismatched at 1 (n = 1) or 2 (n = 3) HLA loci. Diagnoses occurred at 4 to 14 months (median, 6 months) after UCBT, with 4 of 5 patients having preceding grade II to IV acute graft-versus-host disease and 1 being diagnosed at autopsy. Treatment of 4 patients consisted of withdrawal of immunosuppressive treatment and administration of rituximab, with 2 of 4 patients responding. Thus, the incidence of EBV-PTLD after unrelated-donor UCBT appears similar to that observed after transplantation using unrelated bone marrow (BM) and compares favorably with unrelated-donor T-cell-depleted BM transplantation. Because adoptive immunotherapy with donor lymphocytes is not an available option for recipients of unrelated-donor UCBT, new therapeutic strategies are needed, and rituximab appears promising.

Combined mycophenolate mofetil and cyclosporin therapy for severe recalcitrant psoriasis

The use of combination oral therapies in the management of severe psoriasis is gaining increasing acceptance. We report the concurrent use of mycophenolate mofetil (MMF) (maximum dose 3.0 g daily) with low-dose cyclosporin (mean dose 2.5 mg/kg/day) in nine patients with severe psoriasis. All had previously failed on other systemic therapies. They were all initially on treatment with cyclosporin alone which had either failed to clear their psoriasis or they were unable to tolerate higher doses. After the addition of MMF there was good clinical improvement in three patients and moderate disease control in a further four patients after a follow-up period of 3-11 months, with no additional evidence of toxicity at the doses used. We believe that MMF may be useful in some psoriatic patients unresponsive to or intolerant of other treatments or who are at risk of developing nephrotoxicity at higher doses of cyclosporin.

Contrasting patterns of streptococcal superantigen-induced T-cell proliferation in guttate vs. chronic plaque psoriasis

BACKGROUND

Streptococcal infection is strongly associated with guttate psoriasis (GP) and may also exacerbate chronic plaque psoriasis (CPP), possibly through the release of superantigenic toxins.

OBJECTIVES

To investigate superantigen-induced generation of cutaneous lymphocyte associated antigen (CLA) -positive lymphocytes in GP compared with CPP.

METHODS

Peripheral blood lymphocyte (PBL) expression of CLA and T-cell receptor Vbeta chain was assessed in patients with CPP and with active and resolved GP. Expression of superantigen-reactive Vbeta families was compared with in vitro superantigen-induced peripheral blood mononuclear cell (PBMC) proliferation.

RESULTS

Peripheral blood mononuclear cells from patients with active GP showed a twofold increased proliferation after stimulation with streptococcal pyogenic toxins A and streptococcal pyogenic toxins C compared with controls (P < 0.01), whereas the response to the staphylococcal toxins and mitogenic stimulation was the same in all groups. Peripheral blood lymphocytes (PBL) from patients with active GP showed increased use of the superantigen-reactive families Vbeta2 (P < 0.01) and Vbeta17 (P < 0.05), which was not evident in the other patient groups or controls. This pattern of Vbeta expression was only observed in CLA-positive T cells. Furthermore, there was a positive correlation between Vbeta2 expression and enhanced proliferation after stimulation with SPEA (r = 0.82, P < 0.01) and SPEC (r = 0.74, P < 0.05) in active GP.

CONCLUSIONS

This study supports the concept that streptococcal infection precipitates acute GP at least in part through superantigen driven generation of Vbeta-restricted CLA-positive skin homing lymphocytes, whereas we could find no evidence for a similar mechanism occurring in the maintenance of stable CPP.

Early migration of cutaneous lymphocyte-associated antigen (CLA) positive T cells into evolving psoriatic plaques

The majority of T cells in lesional psoriatic skin express the skin homing receptor, cutaneous lymphocyte-associated antigen (CLA). We investigated whether this reflects the selective migration of CLA positive cells into evolving psoriatic plaques, consistent with an important role in disease onset, or whether this occurs in the context of an established cutaneous inflammatory response. We identified the advancing edge of plaques in 16 patients with chronic plaque psoriasis using scanning laser Doppler fluxmetry, and performed immunohistochemical analysis of i) lesional psoriatic skin, ii) clinically normal skin immediately in front of the advancing plaque edge, and iii) uninvolved skin distant from the plaque edge. The T-cell infiltrate was characterized using monoclonal antibodies to CD3, CLA and the integrin alphaEbeta7, which is associated with the retention of lymphocytes at mucosal sites. Epithelial proliferation was assessed using a monoclonal antibody to the nuclear proliferation marker Ki67. There was enrichment of CLA positive T cells in evolving psoriatic skin compared to distant, uninvolved skin (mean CLA positive 75.9% vs 47.8%; P<0.003). This accumulation of CLA positive cells occurred before epidermal hyperproliferation was evident, suggesting that this population of cells plays an important, early role in disease pathogenesis. Established lesional psoriatic skin contained a mixed infiltrate of CLA positive (mean 53.2%) and alphaEbeta7 positive (mean 18.2%) cells, suggesting less tissue-specific T-cell infiltration, although an additional, specific role for alphaEbeta7 in cutaneous inflammation cannot be excluded. Furthermore, this study has highlighted scanning laser Doppler fluxmetry as a useful investigative tool, permitting analysis of the earliest and therefore potentially most important changes in psoriatic plaque formation.

Bone mineral density of patients with chronic plaque psoriasis

Reduced bone mineral density (BMD), the major risk factor for osteoporotic fracture, has been linked to palmoplantar pustular psoriasis, but no significant studies have examined BMD in chronic plaque psoriasis (CPP). In this study, in-patients with severe CPP had their BMD measured at the nondominant hip and lumbar spine using dual energy X-ray absorbtiometry. Ten male and 10 female Caucasian patients were recruited, with a mean age of 47 years (range 20--71 years). There were no significant differences in BMD between patients and controls. However, patients with psoriatic arthropathy in addition to CPP had a significantly lower mean lumbar spine Z-score (- 1.16) than those without arthropathy (+1.38, P = 0.015). Neither previous nor current treatment with systemic steroids, retinoids or methotrexate significantly affected BMD. We found no evidence that patients with CPP, despite risk factors, have a significantly low BMD, although the subgroup with joint involvement appear be at significantly higher risk of osteoporosis and may therefore require preventative treatment.

Immunohistochemical evaluation of psoriatic plaques following selective photothermolysis of the superficial capillaries

BACKGROUND

Elongated and tortuous capillary loops are distinctive features of psoriasis. The significance of these microvascular changes in the pathogenesis of plaques, however, remains unclear.

OBJECTIVES

To determine what part the expanded superficial capillary bed plays in the pathogenesis of clinical lesions by selectively thermolysing psoriatic capillaries with a pulsed dye laser (PDL).

METHODS

Cutaneous lesions were biopsied before and after treatment and sections assessed by standard immunohistochemical techniques for changes in known indicators of angiogenesis, including endothelial surface area, endothelial cell proliferation and endothelial cell expression of adhesion molecules. We also measured lymphocytic infiltration and epidermal thickness, and quantified the presence of a marker of keratinocyte proliferation before and after treatment.

RESULTS

The effect of the PDL was limited to the superficial capillary bed, with no changes in the microvessels (including venules and arterioles) of the upper reticular dermis. Although there was significant clinical improvement in plaques after treatment (P = 0.02), complete clearance of lesions was not achieved. Thermolysis of psoriatic capillaries caused a reduction in both endothelial surface area (P < 0.01) and endothelial cell proliferation in the superficial dermis (P = 0.04). Endothelial expression of surface adhesion molecules (integrins and E-selectin) important in angiogenesis was not, however, altered by treatment. The CD4+ and CD8+ T-cell infiltrate was significantly reduced in the superficial papillary dermis (P = 0.02 and P = 0.04, respectively), but not in the epidermis or upper reticular dermis. Laser treatment significantly reduced epidermal thickness (P = 0.001), but did not alter epidermal keratinocyte proliferation (P = 0.2).

CONCLUSIONS

The results demonstrate that dermal capillary changes alone are unlikely to be causal in psoriasis. They indicate that the expanded psoriatic capillaries may be important in facilitating the access of activated T cells to the skin and in maintaining the psoriatic plaque. These results do not refute the consensus view that plaque formation may be mediated by the release of growth factors/cytokines from activated epidermal T cells/keratinocytes.

Genetic aspects of psoriasis

Epidemiological studies indicate that genes play an important role in the pathogenesis of psoriasis. Multiple genes are likely to be involved, interacting not only with each other but also with the environment to cause disease expression. Molecular genetic studies indicate that there are multiple susceptibility loci present throughout the human genome. It is clear that a gene or genes of major impact on psoriasis is present on chromosome 6 within the major histocompatibility complex (MHC). Linkage disequilibrium studies indicate this gene to reside within a 300 kb interval centred around the centromeric end of class I MHC. Known candidate genes in this region are HLA-C, corneodesmosin and HCR, although novel genes, as yet unknown, may also exist. There is accumulating evidence that HLA-C is not itself the causative gene but rather a marker for it. Identification of the genes involved in psoriasis susceptibility will represent a step forward in our understanding of the disease and our future ability to help patients with psoriasis.

Survival after transplantation of unrelated donor umbilical cord blood is comparable to that of human leukocyte antigen-matched unrelated donor bone marrow: results of a matched-pair analysis

Umbilical cord blood (UCB) is being increasingly used for hematopoietic stem cell transplantation and has been associated with a reduced incidence of severe graft-versus-host disease (GVHD). To further investigate the relative merits of unrelated donor UCB versus bone marrow (BM), a matched-pair analysis comparing the outcomes of recipients of 0 to 3 human leukocyte antigen (HLA)-mismatched UCB and HLA-A, B, DRB1-matched BM was performed. UCB patients, who received cyclosporine (CSA) and methylprednisolone (MP), were matched for age, diagnosis, and disease stage with BM patients, who received either methotrexate (MTX) and CSA (26 pairs) or T-cell depletion (TCD) and CSA/MP (31 pairs). Patients were predominantly children (median age, 5 years) undergoing transplantation for malignancy, storage diseases, BM failure, and immunodeficiency syndromes between 1991 and 1999. Although neutrophil recovery was significantly slower after UCB transplantation, the probability of donor-derived engraftment at day 45 was 88% in UCB versus 96% in BM-MTX recipients (P =.41) and 85% in UCB versus 90% in BM-TCD recipients (P =.32), respectively. Platelet recovery was similar in UCB versus BM pairs. Furthermore, incidences of acute and chronic GVHD were similar in UCB and BM recipients, with 53% of UCB versus 41% of BM-MTX recipients alive (P =.40) and 52% of UCB versus 56% of BM-TCD recipients alive at 2 years (P >.80), respectively. These data suggest that despite increased HLA disparity, probabilities of engraftment, GVHD, and survival after UCB transplantation are comparable to those observed after HLA-matched BM transplantation. Therefore, UCB should be considered an acceptable alternative to HLA-matched BM for pediatric patients.

Identification of a novel psoriasis susceptibility locus at 1p and evidence of epistasis between PSORS1 and candidate loci

The pathogenesis of all forms of psoriasis remains obscure. Segregation analysis and twin studies together with ethnic differences in disease frequency all point to an underlying genetic susceptibility to psoriasis, which is both complex and likely to reflect the action of a number of genes. We performed a genome wide analysis using a total of 271 polymorphic autosomal markers on 284 sib relative pairs identified within 158 independent families. We detected evidence for linkage at 6p21 (PSORS1) with a non-parametric linkage score (NPL)=4.7, p=2 x 10(-6) and at chromosome 1p (NPL=3.6, p=1.9 x 10(-4)) in all families studied. Significant excess (p=0. 004) paternal allele sharing was detected for markers spanning the PSORS1 locus. A further three regions reached NPL scores of 2 or greater, including a region at chromosome 7 (NPL 2.1), for which linkage for a number of autoimmune disorders has been reported. Partitioning of the data set according to allele sharing at 6p21 (PSORS1) favoured linkage to chromosomes 2p (NPL 2.09) and 14q (NPL 2.0), both regions implicated in previous independent genome scans, and suggests evidence for epistasis between PSORS1 and genes at other genomic locations. This study has provided linkage evidence in favour of a novel susceptibility locus for psoriasis and provides evidence of the complex mechanisms underlying the genetic predisposition to this common skin disease.

Long-wave UVA offers partial protection against UVB-induced immune suppression in human skin

Ultraviolet-B (UVB, 280-320 nm) interferes with the generation of cell-mediated immunity to contact allergens applied epicutaneously on the irradiated site. To investigate whether pretreatment with UVA-1 (340-400 nm) protects against the UVB-induced immune suppression we sensitized human volunteers with diphenylcyclopropenone (DPCP) on normal buttock skin (n= 12), on UVB-irradiated buttock skin (n=21), on buttock skin pretreated with UVA-1 (n= 12), and on buttock skin pretreated with UVA-1 and thereafter irradiated with UVB (n=22). Sensitization on UVB-irradiated skin reduced the immunization rate to DPCP compared with sensitization on non-irradiated skin (p<0.01) and skin pretreated with UVA-1 (p<0.01). In contrast, the immunization rate in the group of volunteers sensitized on skin pretreated with UVA-1 before UVB irradiation was significantly higher than the immunization rate in the group of volunteers sensitized on UVB-irradiated skin alone (p<0.05). These results indicate that pretreatment with UVA-1 under certain conditions offers partial protection against the UVB-induced reduction in the immunization rates to epicutaneous allergens.

A double blind, randomized, controlled clinical trial to assess the efficacy of a new coal tar preparation (Exorex) in the treatment of chronic, plaque type psoriasis

Exorex is a new topical formulation for the treatment of psoriasis; it contains 1% coal tar and a synthetic analogue resembling components identified in banana skin (a complex of esterified essential fatty acids). To determine whether the esterified essential fatty acid complex confers any therapeutic advantage over coal tar alone, patients with chronic plaque psoriasis (n = 20) were entered into a double-blind, randomized, right/left comparison of Exorex, and Exorex without the essential fatty acid component (known hereafter as coal tar control) for 8 weeks. Target plaques were scored (0-4) for erythema, desquamation and infiltration at day 0 and at 2 week intervals throughout the study. No significant differences were detected between Exorex and coal tar control with respect to changes in the summed scores at baseline and following 8 weeks of treatment (mean difference in summed score changes from baseline between Exorex and coal tar control 0.2, 95% confidence interval - 0.44 to 0.84; P = 0.52) or in the area under the response-time curve (P = 0.16). Mean percentage improvement in summed scores of target plaques were 53.9% (SE = 4%) and 56.1% (SE = 4.9%) for Exorex and coal tar control, respectively. Results suggest that the complex of esterified essential fatty acids is not exerting any clinically important therapeutic effect in the treatment of chronic plaque psoriasis.

Atypical pigmented lesions following extensive PUVA therapy

We report a 38-year-old woman with psoriasis who developed multiple atypical lentigines following psoralen photochemotherapy (PUVA). The lentigines first appeared 12 years ago, 3 years after she commenced intermittent PUVA treatment. New lesions continued to develop over the subsequent years with further photochemotherapy. Clinically, the lentigines were strikingly atypical, deeply pigmented, dark brown or black, large stellate macules. Histology of a representative lesion was consistent with a PUVA lentigo and no atypical melanocytes were seen. At present, a link between malignant melanoma and PUVA lentigines has not been established. Instead, limited evidence suggests that PUVA lentigines may be more closely linked with the risk of nonmelanoma skin cancer.

Association of TNFA gene polymorphism at position -308 with susceptibility to irritant contact dermatitis

Mechanisms underlying susceptibility to skin irritants are not clearly understood. Cytokines play a key role in inflammation, and functional polymorphisms in cytokine genes may affect responses to irritants. We investigated the relationship between polymorphism in the tumor necrosis factor (TNF) alpha-chain gene and responses to irritants. Volunteers (n=221) tested with sodium dodecyl sulfate (SDS) and benzalkonium chloride (BKC) were divided into responders and nonresponders and high and low irritant-threshold groups. DNA was assayed for the TNF-308 polymorphism by a polymerase chain reaction-restriction fragment length polymorphism method. There was a significant increase in the A allele (P=0.030) and AA genotype (P=0.023) in both the SDS low irritant-threshold group and in SDS responders (A allele P=0.022, AA genotype P=0.048). In the BKC low irritant-threshold group, we found a significant increase in the A allele (P=0.002) and AA genotype (P=0.016). Individuals with a low threshold to both irritants demonstrated a significant increase (P=0.002) in the A allele. This is the first description of a nonatopic genetic marker for irritant susceptibility in normal individuals. Genotyping for the TNF-308 polymorphism may thus contribute to screening of individuals deemed at risk of developing irritant contact dermatitis.

Generalized pustular psoriasis or drug-induced toxic pustuloderma? The use of patch testing

Pustular psoriasis is a rare but serious form of psoriasis. Clinically it may be difficult to differentiate from a pustular drug reaction. We report a case of a generalized pustular eruption triggered by exposure to amoxycillin in a patient with chronic psoriasis. Patch testing to 1% and 5% amoxycillin preparation confirmed a delayed hypersensitivity reaction.

Characterization of the major susceptibility region for psoriasis at chromosome 6p21.3

Psoriasis is a common inflammatory skin condition caused by genetic and environmental factors. Recent genome-wide linkage analyses have identified a locus encoding susceptibility to psoriasis and placed this gene in the 12 cM interval between markers D6S426 and D6S276 on chromosome 6p21.3. This is a broad region and encompasses the human major histocompatibility complex. We have sought to localize the susceptibility gene more precisely by exploiting the linkage, haplotype, and linkage disequilibrium information available through genotyping 118 affected sib pairs, their parents and other affected family members. A total of 14 highly polymorphic markers were genotyped, combining anonymous loci with the class I genes HLA-B and -C distributed across a genetic interval of approximately 14 cM including the entire major histocompatibility complex. Through the application of higher density mapping within the major histocompatibility complex, we identified those regions most commonly shared identical by descent in patients with psoriasis. Using the transmission-disequilibrium test, we found significant evidence of linkage and allelic association across an interval defined by the markers tn62 (p = 1.0 x 10(-7)), HLA-B (p = 4.0 x 10(-7)), and HLA-C (p = 2.7 x 10(-9)), a region encompassed within a 285 kb genomic DNA fragment. Hence these studies contribute to the refinement of the localization of a major psoriasis susceptibility gene and place the critical region near to HLA-C.

Optimising the use of tazarotene in clinical practice: consensus statement from the European advisory panel for tazarotene (Zorac TM)

BACKGROUND

This paper reports the proceedings of the European Advisory Panel Meeting for tazarotene (Zoractrade mark), which took place in Cologne on May 7, 1998.

AIM

The aim of this meeting was to discuss recommendations for the use of tazarotene based on the clinical data available and on the clinical experience of the Advisory Panel members, and to identify future research needs.

RECOMMENDATIONS

Based on currently available data, tazarotene can be used for the treatment of chronic, stable, plaque-type psoriasis, on the trunk or limbs covering up to 20% of the body surface area. In clinical trials, patients generally experienced a clinical response within 4 weeks of starting tazarotene treatment, and improvement was maintained for up to 12 weeks after stopping therapy. Results from published and not yet published clinical trials show that the efficacy and tolerability of tazarotene can be enhanced by the addition of topical corticosteroids to the treatment regimen and that, when used in combination with broad-band UVB phototherapy, tazarotene reduces the amount of UV light required to treat plaques. Tazarotene gel is available in two concentrations, 0.05 and 0.1%. The Advisory Panel recommends that the choice of concentration should be based on factors such as the irritability of the patient's skin and the thickness of plaques. Irritation can be managed by reducing the concentration or frequency of application, or by adding a topical corticosteroid to therapy. Tazarotene shows promise as a treatment for psoriasis in special localisations, such as the scalp, face and skin folds, although clinical studies are required.

Topical maxacalcitol for the treatment of psoriasis vulgaris: a placebo-controlled, double-blind, dose-finding study with active comparator

1alpha, 25-Dihydroxy-22-oxacalcitriol (maxacalcitol) is a vitamin D3 analogue which displays approximately 10 times greater efficacy at suppressing keratinocyte proliferation in vitro than calcipotriol and tacalcitol. To determine clinical efficacy, a phase II double-blind, randomized, left vs. right, concentration-response study was performed with once-daily topical maxacalcitol in patients with mild to moderate chronic plaque psoriasis. Primary efficacy parameters were psoriasis severity index (PSI) based on sum of scores for erythema, scaling and induration and investigators' overall assessment of patients' response to therapy at 8 weeks of treatment. One hundred and forty-four patients participated. All concentrations of maxacalcitol ointment (6, 12.5, 25 and 50 microg/g) were significantly more effective at reducing PSI than placebo (P < 0.01), with greatest effect noted for maxacalcitol 25 microg/g. Calcipotriol ointment 50 microg/g once daily as active comparator had a similar effect. Marked improvement or clearance of psoriasis was greatest for maxacalcitol 25 microg/g (55% of subjects) which compared favourably with calcipotriol (46%). Improvement continued throughout the study period, with no plateau at week 8. Investigators' and patients' side preference (secondary efficacy parameters) rated maxacalcitol more effective than placebo and 25 microg/g maxacalcitol better than calcipotriol (P < 0.05 for investigators' assessment). Twelve patients withdrew from the study due to adverse events, of which four were judged to be due to study medication. This study indicates that once-daily maxacalcitol ointment is effective in the management of plaque psoriasis, with greatest effect noted at 25 microg/g. As no response plateau was noted at 8 weeks, these data suggest that further benefit might be obtained if maxacalcitol ointment were applied for longer. Finally, investigators' overall assessment and side preference suggest that maxacalcitol 25 microg/g may be more effective than once-daily calcipotriol.

Combination treatment with methotrexate and cyclosporin for severe recalcitrant psoriasis

An increasingly important approach to the management of patients with severe psoriasis is the concurrent use of two systemic treatments. Previous guidelines have advised against the use of methotrexate and cyclosporin in combination. We report the successful use of a combination of methotrexate and cyclosporin in the treatment of 19 patients with severe, recalcitrant psoriasis, 15 of whom had psoriatic arthropathy. Most patients had previously received two or more systemic treatments. Before combination treatment was started nine of the patients were taking methotrexate and 10 were taking cyclosporin at the maximum tolerated doses. The duration of combination treatment was bimodally distributed, with seven patients having short-term treatment (mean +/- SD duration 18. 9 +/- 15.7 weeks) and 12 patients having long-term treatment (mean +/- SD duration 193.2 +/- 160.6 weeks). Those patients who received short-term treatment did not develop any evidence of toxicity from either agent. Of those patients on long-term treatment, three developed mild impairment of renal function that returned to normal following a reduction in dose of cyclosporin, and three had impairment of renal function (following long-term cyclosporin monotherapy) that improved, but did not normalize, following a reduction in dose of cyclosporin. In each case, combination treatment for psoriasis resulted in good control of both skin and joint problems using lower doses of each agent than would have been used for monotherapy. We conclude that the combination of methotrexate and cyclosporin is an effective treatment for this group of patients.

Bullous pemphigoid developing during systemic therapy with chloroquine

Bullous pemphigoid has been reported to be induced or precipitated by systemic therapy with several drugs, including penicillamine, captopril, frusemide and ampicillin. We report an African male patient with sarcoidosis who was prescribed chloroquine for progressive dyspnoea. After 3 months he developed generalized pruritus which evolved into a widespread bullous eruption with acral targetoid lesions resembling erythema multiforme. The histological and immunofluorescence findings were diagnostic of bullous pemphigoid. The atypical clinical features of this case resemble the phenotype that has been noted in previous reports of drug-induced bullous pemphigoid.

Increased T-cell receptor vbeta2 chain expression in skin homing lymphocytes in psoriasis

Studies have shown over-representation of certain T-cell receptor (TCR) Vbeta chains in lesional psoriatic skin, implying selection or expansion, possibly by bacterial superantigen. We investigated the pattern of TCR Vbeta chain usage in peripheral blood lymphocytes (PBL) bearing the skin homing receptor cutaneous lymphocyte associated antigen (CLA) in psoriasis patients. Results showed increased expression of TCR Vbeta2 in CLA-positive PBL in psoriasis patients (n = 15) compared with normals (n = 10); P < 0.002. As Vbeta2 is preferentially expressed by lymphocytes responding to certain bacterial superantigens, this study could possibly indicate a role for superantigens in the pathogenesis of psoriasis.

In vivo UVA-1 and UVB irradiation differentially perturbs the antigen-presenting function of human epidermal Langerhans cells

Ultraviolet B (UVB, 290-320 nm) radiation is known to suppress the immune function of epidermal Langerhans cells. We have recently described that in vitro UVB irradiation perturbs the antigen-presenting cell function of Langerhans cells by inhibiting their expression of functional B7 costimulatory molecules (B7-1, B7-2). The aim of this study was to determine wavelength-specific UV effects on Langerhans cells function in vivo, specifically UVB and UVA-1. To address this issue, volunteers were irradiated on the sun protected volar aspects of their forearms with 3 x minimal erythema dose of UVB (Philips TL-12) and UVA-1 (UVASUN 5000 Mutzhaas). Langerhans cells were isolated from suction blister roofs immediately following irradiation. Langerhans cells isolated from UVB- but not from UVA-1-irradiated skin failed to activate naïve resting allogeneic T cells (mixed epidermal cell leukocyte reaction) or primed tetanus toxoid reactive autologous T cells. Langerhans cells isolated from sham-irradiated or UVA-1-irradiated skin strongly upregulated B7-2 molecules during short-term tissue culture. By contrast, Langerhans cells from UVB-irradiated skin did not upregulate B7-2 molecules. Furthermore, exogenous stimulation of the B7 pathway by anti-CD28 stimulatory monoclonal antibodies restored the capacity of UVB-irradiated Langerhans cells to activate both alloreactive and tetanus toxoid-reactive T cells, implying suppressed antigen-presenting cell activities and perturbed B7 expression of Langerhans cells isolated from UVB-irradiated skin are related. Those studies demonstrate that in vivo UVB, but not UVA-1, interferes with the activation-dependent upregulation of B7 molecules on Langerhans cells, which in turn is of functional relevance for the perturbed antigen-presenting cell function of Langerhans cells within UVB- but not UVA-1-irradiated skin.

Ultraviolet B induced suppression of induction of contact sensitivity in human skin is not associated with tumour necrosis factor-alpha-308 or interleukin-10 genetic polymorphisms

Low doses of ultraviolet B (UVB) can induce localized immunosuppression in skin. This effect may be important in the induction of skin cancers and is thought to be mediated by tumour necrosis factor (TNF) alpha and interleukin (IL) 10 in conjunction with other factors. In humans a transition polymorphism in the TNF-alpha gene may affect TNF-alpha secretion and the promoter region of the IL-10 gene contains a CA repeat polymorphism which may affect gene function. We have therefore investigated the association of these polymorphisms with UVB-induced immunosuppression in humans. Volunteers (n = 42) were irradiated with UVB then sensitized on irradiated skin with diphenylcyclopropanone (DPCP) and subsequently antigen challenged with DPCP. DNA was extracted from blood samples and volunteers genotyped for the TNF-alpha polymorphism by polymerase chain reaction (PCR) and restriction digestion. The CA repeat polymorphism was amplified by PCR and sized by gel electrophoresis. Twenty-four volunteers were susceptible to UVB-induced immunosuppression and 18 were resistant. The association of allele frequencies and phenotype was statistically tested using a chi2-test. For both the TNF-alpha and IL-10 polymorphisms, there was no statistically significant association between allele types and response to UVB. These results indicate that variation in the immune response to UVB in humans is not associated with the TNF-alpha-308 transition or IL-10 CA repeat polymorphisms, although other as yet undetected DNA sequence variants of these genes may be involved.

Effect of granulocyte macrophage-colony stimulating factor on Langerhans cells in normal and healthy atopic subjects

Granulocyte macrophage-colony stimulating factor (GM-CSF) is a multipotent cytokine produced by many cutaneous cell types including keratinocytes. Langerhans cells (LC) represent the major antigen-presenting cells in skin, and in vitro studies demonstrate that GM-CSF is of pivotal importance in LC. Healthy volunteers (n = 3 non-atopic, n = 3 with atopy) received recombinant human GM-CSF (0. 05 microg/mL) by intradermal injection for 3 days to the same site. Diluent was injected in a similar manner as control. Biopsies were taken 24 h after the final injection and examined immunohistochemically for LC and inflammatory cell markers. Compared with control sites, intradermal GM-CSF resulted in shortening of dendritic cell processes and redistribution of LC in the epidermis; numbers of CD1a + cells in the epidermis were significantly decreased (P < 0.005), while those in the dermis were significantly increased (P < 0.05) following intradermal GM-CSF when compared with controls. Double labelling studies on epidermal CD1a + cells indicated de novo expression of intercellular adhesion molecule (ICAM)-1 and increased expression of HLA-DR following GM-CSF (P < 0. 005, P < 0.005, respectively). Additional findings included a marked mixed inflammatory cell infiltrate in the dermis and increased expression of the endothelial cell adhesion molecules E-selectin and ICAM-1. These data indicate that in normal human skin, GM-CSF induces changes in the phenotype and distribution of CD1a + cells consistent with LC functional maturation and exit from the epidermis to the dermis. As these events are central to the initiation of cutaneous inflammation, GM-CSF may potentially play a critical role in the pathogenesis of inflammatory dermatoses.

Psoriasis as a T cell-mediated autoimmune disease

Psoriasis is a common chronic skin disease in which T lymphocytes are thought to play a vital pathogenic role. Evidence shows that these are activated memory skin-homing T cells which induce characteristic disease features via cytokine production. Understanding the mechanisms of T cell accumulation in skin and mediation of psoriasis is critical to designing immunotherapy for this distressing disease.

Susceptibility to effects of UVB irradiation on induction of contact sensitivity, relevance of number and function of Langerhans cells and epidermal macrophages

Sensitization on skin exposed to acute low-dose UVB irradiation separates normal humans into two phenotypically distinct groups: One group, following sensitization on UVB-irradiated skin, develops contact sensitivity, designated UVB resistant (UVB-R) and the second group, following sensitization on UVB-irradiated skin, fails to develop contact sensitivity, designated UVB susceptible (UVB-S). To investigate whether UVB susceptibility in humans in related to antigen-presenting activity in the skin we studied the effect of UVB irradiation on the number and function of the epidermal antigen-presenting cells in volunteers identified as UVB-R and UVB-S. Single cell suspensions of epidermal cells from control skin and skin exposed to 3 minimal erythema doses (MED) of UVB 3 days previously were stained for Langerhans cells (CD1a+HLA-DR+) and epidermal macrophages (CD1a-HLA-DR+). The UVB exposure of the skin significantly decreased the percentage of Langerhans cells (UVB-R: n = 7, P < 0.02, UVB-S: n = 6, P < 0.03) and increased the percentage of epidermal macrophages (UVB-R: n = 7, P < 0.03, UVB-S: n = 6, P < 0.03) however to the same degree in both the UVB-R and the UVB-S group. To study the effect on Langerhans cell alloreactivity, epidermal cells were harvested immediately after UVB irradiation. However, in both UVB-R and UVB-S subjects the Langerhans cell alloreactivity was blocked to the same degree immediately after UVB irradiation compared to nonirradiated epidermal cells. To determine the effect of UVB irradiation on epidermal macrophages, epidermal cells were harvested 3 days after UVB irradiation. Irradiated epidermal cells from both UVB-R and UVB-S subjects demonstrated a strong antigen-presenting capacity compared to epidermal cells from control skin leading to activation of T cells that mainly secrete interferon (IFN)-gamma and not interleukin (IL)-4. In conclusion we found that UVB susceptibility was not correlated with the number of Langerhans cells or epidermal macrophages in the skin at the same time of sensitization. Neither was it correlated with the capacity of Langerhans cells nor UVB-induced epidermal macrophages to activate T cells in vitro.

Contrasting effects of ultraviolet A1 and ultraviolet B exposure on the induction of tumour necrosis factor-alpha in human skin

Ultraviolet B (UVB) irradiation of the skin causes immunosuppression which is relevant to the induction of skin cancer. The mechanism of this immunomodulation is unclear but various regulatory molecules have been implicated, including cis-urocanic acid (cis-UCA) and the cytokines tumour necrosis factor-alpha (TNF-alpha) and interleukin 10 (IL-10). Whether ultraviolet A (UVA) induces similar changes has not been investigated fully. We studied the effect of in vivo UVB and long-wave UVA (UVA1) exposure on the induction of TNF-alpha, IL-10 and cis-UCA in human skin. Volunteers were irradiated with three minimal erythema doses (MED) of UVB or UVA1. At different times after irradiation, suction blisters were raised from irradiated and from non-irradiated (control) skin. The TNF-alpha and IL-10 protein concentration, and the percentage of cis-UCA in the blister fluid, were then determined. UVB irradiation of human skin led to a rapid and significant increase in TNF-alpha concentration in suction-blister fluid, with maximal values 6 h after irradiation (n = 6, P < 0.05). In contrast, UVA1 irradiation led to a decrease in TNF-alpha concentration in the suction-blister fluid compared with non-irradiated skin, with the lowest values 6 h after irradiation (n = 6, P < 0.05). Both UVB and UVA1 exposure of the skin induced a slight increase in IL-10 concentration. However, the increase in IL-10 was only significant after UVB irradiation (UVB, n = 6, P < 0.05; UVA, n = 7, P < 0.1). As previously shown, both UVB and UVA1 result in the photo-isomerization of trans-UCA and an increased percentage of cis-UCA was found in the suction-blister fluid. Thus the results show differential effects of UVB and UVA1 irradiation on the induction of immunoregulatory molecules, which may help to explain the variation in immune responses after UVB and UVA1 exposure of human skin.

CD44 variant expression in cutaneous T-cell lymphoma

Expression of the lymphocyte homing receptor CD44 and its splice variants have been linked to tumour dissemination and poor prognosis in non-Hodgkin's lymphoma. Specifically, the in vitro expression of variant exon V6 confers metastatic potential in rat pancreatic carcinoma cell lines. In this study, we investigated the expression of CD44 splice variants in cutaneous T-cell lymphomas, including patients with mycosis fungoides (MF), Sezary syndrome (SS), large-cell anaplastic lymphoma (LCAL) and HTLV1-associated cutaneous lymphoma. In addition, 4 involved lymph nodes from 2 patients with MF and 1 patient with SS were examined. Inflammatory dermatoses, lichen planus and psoriasis, and normal skin were also studied. Immunohistochemistry was performed using a panel of monoclonal antibodies, including those with specificity for CD44H (standard isoform) and variant exons V3, V6 and V8-9. Normal epidermal keratinocytes were consistently CD44H and CD44 V3, V6 and V8-9 positive. In all the different clinicopathological subtypes and stages of cutaneous T-cell lymphomas, including involved lymph nodes, tumour cells consistently expressed CD44H, but were CD44 V3 and V6 negative. CD44 V8-9 was expressed on a majority of tumour cells in 2/5 LCAL and on occasional tumour cells in 2/5 LCAL. Occasional V8-9 positive tumour cells were also identified in 6/13 MF, 1/4 SS and 3/4 HTLV1. In 2/3 lymph node samples from 2 patients with tumour-stage MF, CD44 V8-9 expression was found on a small percentage of atypical mononuclear cells. Scattered V8-9 positive dermal mononuclear cells were present in sections of lichen planus and psoriasis. We have found no evidence to suggest that the metastasis-associated CD44 variant exon (V6) is expressed in cutaneous T-cell lymphoma, or that CD44H expression is associated with an adverse prognostic group. It is not clear whether the strong expression of CD44 V8-9 in 2 patients with CD30 positive LCAL reflects activation status or metastatic potential.

Localization of endothelial proliferation and microvascular expansion in active plaque psoriasis

Expansion of the dermal microvasculature is a prominent feature of psoriasis. Although the pathogenetic process resulting in vascular morphological changes remains unclear, considerable evidence suggests the involvement of angiogenesis. To assess the degree and site of psoriatic microvascular expansion, immunohistochemical studies were performed on paired lesional and non-lesional specimens from 10 patients with active, untreated plaque psoriasis. Five-micron thick sections were labelled with monoclonal antibody JC/70A specific for the endothelial marker CD31, and vascular quantification was achieved using hue-saturation-intensity image analysis. Assessment of vasculature in the papillary dermis (superficial plexus) demonstrated a fourfold increase in endothelial surface area of lesional compared with non-lesional skin (P < 0.01), while there was no significant increase in vasculature of the upper reticular dermis. Subsequently, 18-micron thick sections were double-labelled with MIB-1 antibody to the nuclear proliferation marker Ki-67 and JC/70A. Endothelial cell proliferation was identified in the vertical limbs of capillary loops in eight out of 10 lesional biopsies and in no non-lesional biopsies. The endothelial MIB-1 labelling index was 3.1% of total endothelial cells of the superficial plexus. These findings confirm endothelial proliferation underlying psoriatic microvascular expansion, and indicate that this process is limited to a specific site in the dermal capillary bed.

Identification of a major susceptibility locus on chromosome 6p and evidence for further disease loci revealed by a two stage genome-wide search in psoriasis

Psoriasis is a common chronic inflammatory disorder of the skin. To further understand the pathogenesis of psoriasis we have chosen to investigate the molecular genetic basis of the disorder. We have used a two-stage approach to search the human genome for the location of genes conferring susceptibility to psoriasis, using a total of 106 affected sibling pairs identified from 68 independent families. As over a third of the extended kindreds included affected relatives besides siblings, in addition to an analysis of allele sharing between affected sibling pairs, a novel linkage strategy was applied that extracts full non-parametric information. Four principal regions of possible linkage were identified on chromosomes 2, 8, 20 (p <0.005) and markers from the MHC region at 6p21 (p <0.0000006) for which significant evidence of linkage disequilibrium was also observed (p <0.00002). Whilst data from limited case control associations exist to implicate the MHC, the results of this genome wide analysis demonstrate that, at least in the population studied, a gene or genes located within the MHC and close to the class 1 HLA loci, represent the major determinant of the genetic basis of psoriasis.