Drug Survival, Safety, and Effectiveness of Biologics in Older Patients with Psoriasis: A Comparison with Younger Patients-A BioCAPTURE Registry Study.

BACKGROUND: Psoriasis is a common inflammatory disease in any age group, but also in older patients (≥ 65 years of age). Since older patients are often excluded from clinical trials, limited data specifically on this growing population are available, e.g. regarding the safety and performance of biological treatment. AIMS: We aimed to give insight into this specific population by comparing the drug survival and safety of biologics in older patients with that in younger patients. METHODS: In this real-world observational study, data from 3 academic and 15 non-academic centers in The Netherlands were extracted from the prospective BioCAPTURE registry. Biologics included in this study were tumor necrosis factor (TNF)-α, interleukin (IL)-17, IL-12/23, and IL-23 inhibitors. Patients were divided into two age groups: ≥ 65 years and < 65 years. The Charlson Comorbidity Index (CCI) was used to measure comorbid disease status, and all adverse events (AEs) that led to treatment discontinuation were classified according to the Medical Dictionary for Regulatory Activities (MedDRA) classification. All AEs that led to treatment discontinuation were studied to check whether they could be classified as serious AEs (SAEs). Kaplan-Meier survival curves for overall 5-year drug survival and split according to reasons of discontinuation (ineffectiveness or AEs) were constructed. Cox regression models were used to correct for possible confounders and to investigate associations with drug survival in both age groups separately. Psoriasis Area and Severity Index (PASI) scores during the first 2 years of treatment and at the time of treatment discontinuation were assessed and compared between age groups. RESULTS: A total of 890 patients were included, of whom 102 (11.4%) were aged ≥ 65 years. Body mass index, sex, and distribution of biologic classes (e.g. TNFα, IL12/23) were not significantly different between the two age groups. A significantly higher CCI score was found in older patients, indicative of more comorbidity (p < 0.001). The 5-year ineffectiveness-related drug survival was lower for older patients (44.5% vs. 60.5%; p = 0.006), and the 5-year overall (≥ 65 years: 32.4% vs. < 65 years: 42.1%; p = 0.144) and AE-related (≥ 65 years: 82.1% vs. < 65 years: 79.5%; p = 0.913) drug survival was comparable between age groups. Of all AEs (n = 155) that led to discontinuation, 16 (10.3%) were reported as SAEs but these only occurred in younger patients. After correcting for confounders, the same trends were observed in the drug survival outcomes. Linear regression analyses on PASI scores showed no statistical differences at 6, 12, 18, and 24 months of treatment between age groups. CONCLUSIONS: This study in a substantial, well-defined, prospective cohort provides further support that the use of biologics in older patients seems well-tolerated and effective. Biologic discontinuation due to AEs did not occur more frequently in older patients. Older patients discontinued biologic treatment more often due to ineffectiveness, although no clear difference in PASI scores was observed. More real-world studies on physician- and patient-related factors in older patients are warranted.

The relative effectiveness of eribulin for advanced breast cancer treatment: a study of the southeast Netherlands advanced breast cancer registry.

Background: Eribulin provided significant overall survival (OS) benefit in heavily pretreated advanced breast cancer patients in the EMBRACE trial. We investigated the use of eribulin in daily clinical practice, the relative effectiveness of eribulin versus non-eribulin chemotherapy, and the safety of eribulin in real-world patients included in the SOutheast Netherlands Advanced BREast cancer (SONABRE) registry.Material and methods: Patients treated with eribulin and eligible patients for eribulin who received a different chemotherapy (i.e., non-eribulin group) in ten hospitals in 2013-2017 were included. A multivariate matching algorithm was applied to correct for differences in baseline characteristics between the groups, including the number of previous treatment lines. Progression-free survival (PFS) and OS of eribulin were compared with the matched non-eribulin group through Kaplan-Meier curves and multivariate Cox proportional hazard models. The occurrence of dose delay and reduction was described.Results: Forty-five patients received eribulin according to its registration criteria and 74 patients were eligible for eribulin but received non-eribulin chemotherapy. Matching increased the similarity in baseline characteristics between the eribulin and non-eribulin groups. Median PFS was 3.5 months (95% confidence interval (CI): 2.7-5.5) in the eribulin group and 3.2 months (95% CI: 2.0-4.8) in the matched non-eribulin group (adjusted hazard ratio (HR): 0.83, 95% CI: 0.49-1.38). Median OS was 5.9 months (95% CI: 4.6-11.0) and 5.2 months (95% CI: 4.6-9.5) in the eribulin and non-eribulin groups, respectively (adjusted HR: 0.66, 95% CI: 0.38-1.13). Dose delay or reduction occurred in 14 patients (31%) receiving eribulin.Conclusions: No difference in PFS and OS was observed between eribulin and non-eribulin treated patients. Eribulin had a manageable toxicity profile.

Female patients are less satisfied with biological treatment for psoriasis and experience more side-effects than male patients: results from the prospective BioCAPTURE registry.

BACKGROUND: Female sex has been reported as a predictor for treatment discontinuation with biological therapies for psoriasis, although reasons remain unclear. It can be hypothesized that lower satisfaction with biological treatment in women might add to the lower drug survival rates. OBJECTIVES: To identify possible differences in satisfaction with biological treatment between female and male patients using the Treatment Satisfaction Questionnaire for Medication (TSQM). METHODS: Data of psoriasis patients treated with biologics were obtained from the prospective, multicentre, daily-practice BioCAPTURE registry. Longitudinal TSQM data were analysed by linear mixed models. Relevant patient characteristics were incorporated as possible confounding factors. Post hoc analysis of adverse events was performed in order to investigate differences between sexes. RESULTS: We included 315 patients with 396 corresponding treatment episodes (137 adalimumab, 90 etanercept, 137 ustekinumab, 24 secukinumab and 8 infliximab). Almost forty per cent of the patients were female. Women had significantly lower baseline PASI scores (P = 0.01). Longitudinal analyses demonstrated lower TSQM scores for 'side-effects' (P = 0.05) and 'global satisfaction' (P = 0.01) in female patients compared with male patients over 1 year of treatment. Women reported more relevant adverse events in the context of biologic treatment compared to men (rate ratio 1.79; P < 0.001), with more fungal (rate ratio 2.20; P = 0.001) and herpes simplex infections (rate ratio 3.25; P = 0.005). CONCLUSIONS: This study provides a prospective, longitudinal analysis of treatment satisfaction with biologics in female and male patients with psoriasis. Women were slightly less satisfied with treatment regarding side-effects and global satisfaction. Differences in treatment satisfaction and side-effects might add to the fact that women discontinue biological treatments more often.

Frequency and predictors of a high clinical response in patients with psoriasis on biological therapy in daily practice: results from the prospective, multicenter BioCAPTURE cohort.

BACKGROUND: It is important to assess which patients with psoriasis are more likely to achieve high clinical responses on biologics. OBJECTIVES: To assess the number of treatment episodes (TEs) that achieve a 100% improvement in Psoriasis Area and Severity Index (PASI 100), PASI 90 or PASI ≤ 5 at week 24 of biological treatment, and which baseline patient characteristics predict treatment response. METHODS: Data from patients with psoriasis treated with adalimumab, etanercept, infliximab or ustekinumab were extracted from a prospective cohort. TEs with high clinical responses were described. Uni- and multivariate regression analyses were performed with the generalized estimating equation method to elucidate which baseline patient characteristics were predictors for PASI 90 and PASI ≤ 5 at week 24. RESULTS: In total, 454 TEs were extracted (159 adalimumab; 193 etanercept; 19 infliximab; 83 ustekinumab) from 326 patients. At week 24, in 3%, 15% and 59% of TEs, respectively, PASI 100, PASI 90 and PASI ≤ 5 was reached. In TEs without a PASI 100 or PASI 90 response, PASI ≤ 5 was still achieved in 58% and 52%, respectively. Baseline PASI ≥ 10 was a strong predictor for achieving PASI 90; baseline PASI < 10 and a lower baseline body mass index (BMI) were significant predictors for PASI ≤ 5 at week 24. CONCLUSIONS: A limited number of patients achieved PASI 100 or PASI 90 at 24 weeks of biological treatment. Including an absolute PASI score in the assessment of psoriasis severity is important. Baseline BMI was an important, modifiable predictor for a high response.

Comparison of the 1- and 5-year effectiveness of adalimumab, etanercept and ustekinumab in patients with psoriasis in daily clinical practice: results from the prospective BioCAPTURE registry.

BACKGROUND: The efficacy of etanercept and ustekinumab in psoriasis has been compared in one randomized controlled trial. Comparison of the long-term effectiveness of biologics in daily-practice psoriasis treatment is currently lacking. OBJECTIVES: To compare the effectiveness between the three widely used outpatient biologics adalimumab, etanercept and ustekinumab in daily-practice psoriasis treatment and to correct for confounders. METHODS: Data were extracted from the prospective, multicentre BioCAPTURE registry. Multilevel linear regression analyses (MLRAs) and generalized estimating equation (GEE) analyses were performed on the course of mean Psoriasis Area and Severity Index (PASI) and PASI 75 (≥ 75% reduction vs. baseline). Both models were corrected for confounders. Subgroup analyses for biological dose were performed. RESULTS: We included 356 patients with 513 treatment episodes: 178 adalimumab, 245 etanercept and 90 ustekinumab. MLRA showed a similar effectiveness between adalimumab, etanercept and ustekinumab after 1 year, but the highest effectiveness for ustekinumab during 5 years of treatment (P = 0·047; ustekinumab vs. etanercept, P = 0·019). GEE analysis revealed a higher chance of attaining PASI 75 with adalimumab and ustekinumab than with etanercept at 1 year of treatment. A higher than label dose was more often used in patients treated with etanercept (adalimumab, etanercept and ustekinumab: respectively 31·5%, 55·1% and 17% after 1 year, P < 0·001; 39·3%, 71·4% and 24% after 5 years, P < 0·001). CONCLUSIONS: Compared with etanercept, ustekinumab had the highest effectiveness during 5 years of treatment. Patients receiving adalimumab and ustekinumab more often reached PASI 75 than those on etanercept at 1 year of treatment. Dose escalation was more frequent in etanercept and adalimumab than in ustekinumab.

Body mass index predicts discontinuation due to ineffectiveness and female sex predicts discontinuation due to side-effects in patients with psoriasis treated with adalimumab, etanercept or ustekinumab in daily practice: a prospective, comparative, long-term drug-survival study from the BioCAPTURE registry.

BACKGROUND: Predictors for successful treatment are important for personalized medicine. Predictors for drug survival of biologics in psoriasis have been assessed, but not split for different biologics or for the reason of discontinuation. OBJECTIVES: To compare long-term drug survival between the outpatient biologics adalimumab, etanercept and ustekinumab in patients with psoriasis, and to elucidate predictors for overall survival and drug discontinuation due to ineffectiveness and side-effects for each biologic separately. METHODS: Ten years of data were extracted from the prospective, multicentre, long-term BioCAPTURE registry. Kaplan-Meier survival analyses and confounder-corrected multivariate Cox regression analysis for drug survival (MCR-DS) were performed to compare drug survival between biologics. To elucidate the predictors for different reasons of discontinuation for each biologic, univariate Cox regression analyses and multivariate Cox regression analyses for predictors (MCR-P) with backward selection were performed. RESULTS: In total, 526 treatment episodes - 186 adalimumab, 238 etanercept and 102 ustekinumab - were included covering 1333 treatment years. MCR-DS showed a significantly higher overall survival for ustekinumab compared with adalimumab and etanercept. MCR-P showed that higher body mass index (BMI) was a predictor for discontinuation due to ineffectiveness for etanercept and ustekinumab and that female sex was a predictor for discontinuation due to side-effects for adalimumab, etanercept and ustekinumab. CONCLUSIONS: Ustekinumab has the highest confounder-corrected long-term drug survival in psoriasis treatment, compared with adalimumab and etanercept. Higher BMI is a predictor for discontinuation due to ineffectiveness in etanercept and ustekinumab, and female sex is a consistent predictor for discontinuation due to side-effects in all three outpatient biologics.

Comparing treatment goals for psoriasis with treatment decisions in daily practice: results from a prospective cohort of patients with psoriasis treated with biologics: BioCAPTURE.

BACKGROUND: Treatment goals have been developed to optimize daily clinical practice psoriasis care, but have not yet been studied in real life. OBJECTIVES: To investigate to what extent treatment decisions made by dermatologists in daily clinical practice for patients with psoriasis on biologics are already in accordance with treatment goals without the active application of the treatment goals algorithm. METHODS: Data were extracted from a prospective daily practice cohort of patients with psoriasis on biologics. Analysis was done on effectiveness (Psoriasis Area and Severity Index score) and quality of life (Dermatology Life Quality Index questionnaire). Treatment decisions such as dosage adjustments, combination treatments, or switching therapy were compared with the treatment goals algorithm. RESULTS: In 64% (253 of 395) of visits, physicians followed the treatment goals algorithm. There were 162 (41%) visits in which there should have been a treatment modification according to treatment goals (group Modify) and a modification was indeed made in 59 of these 162 visits (36%). In 233 (59%) visits no treatment modification was necessary (group Continue) and therapy was indeed not modified in 194 of 233 visits (83%). CONCLUSIONS: Physicians acted in accordance with treatment goals in the majority of patient visits. In the patient group not achieving these goals, physicians should have modified therapy according to treatment goals but continued the same therapeutic regimen in the majority of visits. Optimizing therapy and defining barriers in the latter group might increase treatment results in daily practice psoriasis care.

'Happy' drug survival of adalimumab, etanercept and ustekinumab in psoriasis in daily practice care: results from the BioCAPTURE network.

BACKGROUND: Drug survival is a marker for treatment success. To date, no analyses relating dermatological quality-of-life measures to drug survival have been published. OBJECTIVES: (i) To describe 1-year drug survival for adalimumab, etanercept and ustekinumab in a daily practice psoriasis cohort, and (ii) to introduce the concept of 'happy' drug survival, defined as Dermatology Life Quality Index (DLQI) ≤ 5 combined with being 'on drug' at a specific time point. METHODS: Data were extracted from a prospective registry. Drug survival was analysed using Kaplan-Meier estimates. 'Happy' drug survival was calculated, with data split into 'happy' (DLQI ≤ 5) vs. 'unhappy' (DLQI > 5) at baseline and months 3, 6, 9 and 12. RESULTS: 249 treatment episodes were included (101 adalimumab, 82 etanercept, 66 ustekinumab). The 1-year drug survival rates for ustekinumab, adalimumab and etanercept were 85%, 74% and 68%, respectively. Ustekinumab showed a better confounder-corrected drug survival vs. etanercept [hazard ratio (HR) 3·8, P = 0·02] and a trend towards better survival vs. adalimumab (HR 2·3, P = 0·1). At baseline, the majority (n = 115, 73%) was considered 'unhappy' and a minority 'happy' (n = 42, 27%) (ratio 'happy':'unhappy' was 1 : 2.7). The percentage of treatment episodes with 'happy' on-drug patients increased to 79% after 1 year. CONCLUSIONS: Ustekinumab showed a better overall drug survival than etanercept, and a trend towards a better overall drug survival than adalimumab. After 1 year, patients reported to be 'happy' in 79% of episodes and 'unhappy' in 21%. We introduced the new concept of 'happy' drug survival because the proportion of on-drug patients with good quality of life is an important indicator for treatment success.

Satisfaction of treatment with biologics is high in psoriasis: results from the Bio-CAPTURE network.

BACKGROUND: Although the effectiveness of biologics for psoriasis has been measured extensively with objective outcome measures, studies based on subjective, patient-reported outcome measures remain scarce. OBJECTIVES: To investigate satisfaction with medication, as measured by the Treatment Satisfaction Questionnaire for Medication (TSQM) for biologics in daily practice psoriasis care in the first 6 months of treatment; and to identify possible differences in satisfaction with medication between patients experienced (biologics-experienced) and inexperienced (biologics-inexperienced) in the use of biologics. METHODS: TSQM baseline measurements were compared using measurements taken after 6 months, using the Wilcoxon signed-rank test for paired comparisons. Intention-to-treat with last observation carried forward (ITT with LOCF) and as-treated analyses were performed. The difference between biologics-experienced and biologics-inexperienced patients for TSQM was analysed using ITT with LOCF. At 6 months, outcomes for biologics-experienced and biologics-inexperienced patients were compared using the Mann-Whitney U-test. RESULTS: One hundred and six patients were eligible for analysis, and treated with etanercept (n = 34), adalimumab (n = 49) or ustekinumab (n = 23). Fifty-four per cent of patients were biologics-inexperienced. A statistically significant improvement was seen in all domains of the TSQM ('effectiveness', 'side-effects', 'convenience' and 'global satisfaction') by comparison of months 3 or 6 with baseline (all P ≤ 0·02). After 6 months, biologics-inexperienced patients scored better on the 'global satisfaction' domain than biologics-experienced patients (P < 0·01). CONCLUSIONS: We provide a prospective, longitudinal analysis of TSQM for biologics in daily practice psoriasis care. High satisfaction rates were achieved. The 'effectiveness' and 'convenience' domains showed the most room for improvement.

Low-molecular-weight model study of peroxide cross-linking of ethylene-propylene (-diene) rubber using gas chromatography and mass spectrometry I. Combination reactions of alkanes.

The combination reaction of linear and branched alkanes, initiated by dicumylperoxide, has been studied as a model for the combination cross-linking reaction of peroxide-cured terpolymerised ethylene, propylene and diene monomer. Both gas chromatography-mass spectrometry (GC-MS) and comprehensive two-dimensional GC-MS (GCxGC-MS) analyses have been employed to analyse the isomeric reaction products. The identification of these products based on their MS fragmentation patterns is quite complex, due to the high tendency of random rearrangements. Careful elucidation of the high-mass ions at optimised ionisation energy (55eV) has resulted in proposed structures for the different isomeric reaction products. The structure assignment by MS is in agreement with the GCxGC elution pattern and with the result of a theoretical model to predict the boiling points and, thus, the GC retention times. In addition, a model that provided a direct correlation between chemical structure and retention times was developed and this was found to provide a useful fit. Quantification of the identified reaction products by GC separation and flame ionization detection allows classification according to the hydrogen abstraction sites for the alkanes by dicumylperoxide. The selectivity for hydrogen abstraction generally follows the expected order, but a higher reactivity was observed for the methylene group next to a primary methyl group, while a reduced reactivity of the methylene group next to ethyl and to methyl groups was observed. The used approach proved to be a very powerful tool to enhance our understanding of the mechanism of peroxide cross-linking of (branched) alkanes.

Do Dutch dermatologists care for venereology? An inquiry among all non-academic dermatologists in The Netherlands.

The financing of STD outpatient clinics in The Netherlands is currently undergoing structural changes. Because these changes also have implications for the infrastructure of STD care as a whole, the STD committee of the Dutch Society for Dermatology and Venereology (STD committee NVDV) and the National Society of Municipal Health Services (GGD-Nederland) are currently exploring the possibilities and feasibility of intensified regional collaboration between Municipal Health Services (MHSs) and dermatologists. However, for fruitful collaboration it is essential that a substantial number of dermatologists has an interest in STD care. Therefore, the STD committee NVDV has conducted a structured survey in order to study the support of Dutch dermatologists for such a regional collaboration. In this paper, the results of the survey are presented. It appears that the majority of Dutch dermatologists is (still) interested in STD, and although a minority currently collaborates with local MHSs on a regular basis, a large group is willing to do so in the future. We conclude that the majority of dermatologists in the Netherlands (still) cares for venereology and that there is a sound basis for a fruitful cooperation with MHSs.

Changes in keratin 6 and keratin 10 (co-)expression in lesional and symptomless skin of spreading psoriasis.

BACKGROUND: Keratin 6 (K6) and keratin 10 (K10) are markers for epidermal hyperproliferation and differentiation, respectively, and are both expressed in the suprabasal layers of the epidermis. They may be co-expressed in different stages of the spreading psoriatic lesion, but single expression can also occur. OBJECTIVE: To investigate to what extent keratinocytes express K6 and K10, and to what extent they co-express K6 and K10 in different stages of the psoriatic lesion. We studied this in spreading psoriatic plaques. METHODS: Three 3-mm punch biopsies were obtained from the inner involved margin of a spreading lesion, from the uninvolved skin immediately adjacent to the spreading plaque, and from the distant uninvolved skin of 8 patients with incipient psoriasis. From 9 healthy volunteers, 3-mm punch biopsies were obtained as controls. After preparation of single cell suspensions of these biopsies, a triple staining protocol was performed with markers for K6 (monoclonal antibody LHK6B), K10 (monoclonal antibody RKSE60) and DNA content (TO-PRO-3 iodide). Subsequently, cells were measured with a flow cytometer and the proportion of the markers was calculated using specific software. RESULTS: We observed a population of K6/K10-co-expressing cells, but also populations expressing only K6. These subpopulations varied with the involvement of the lesion. There was a statistically significant difference between the inner margin and the outer margin with respect to the proportion of K6- and K10-expressing cells, whereas more K6-positive and K10-negative cells were detected in the inner margin of the lesions. The proportion of K6/K10-co-expressing cells in the inner margin was significantly different from the distant uninvolved skin. CONCLUSION: We confirmed that individual keratinocytes in psoriasis can express K6 or K10 depending on their localization in involved or uninvolved skin. There is a unique subpopulation of cells in the psoriatic plaques which co-express K6 and K10. More studies are required to fully understand the pathogenic relevance of co-expression and single expression of K6 and K10.

CD 2394, a novel synthetic retinoid, initiates an embryonic type of differentiation in hyperproliferative skin.

In human skin, there are 2 types of epidermal differentiation: normal differentiation, characterized by keratin 10 expression, and alternative differentiation. Alternative differentiation may be regeneration-associated differentiation (keratin 6 and 16) or re-induction of embryonic differentiation (expression of keratin 13, 15 and 19). The purpose of this study was to investigate the effect of the novel synthetic retinoid CD 2394 on hyperproliferative human skin, with respect to embryonic differentiation in particular. The effects of CD 2394 were compared with untreated and vehicle-treated skin 48 h after tape-stripping. In a multiparameter flow cytometric assay, parameters of proliferation, normal differentiation, embryonic differentiation and inflammation were assessed. With respect to proliferation, treatment with CD 2394 resulted in a decreased number of cells in the G2M-phase. Normal differentiation was decreased in CD 2394 treated skin. Furthermore, most of the CD 2394 treated samples showed expression of keratin 13, which was not seen in the otherwise treated skin. A correlation between keratin 10 and keratin 13 expression could not be demonstrated. This study showed that CD 2394 is capable of inducing an embryonic pathway of differentiation, which is distinct from normal differentiation or regeneration-associated differentiation.

VML 295 (LY-293111), a novel LTB4 antagonist, is not effective in the prevention of relapse in psoriasis.

Leukotriene B4 (LTB4) receptor antagonists have been the subject of several studies in the treatment of inflammatory diseases, including psoriasis. A novel oral LTB4 antagonist, VML 295 (LY-293111) has recently been developed and has a pronounced effect on epidermal inflammatory parameters. However, oral treatment of psoriasis for 4 weeks did not result in a decrease in disease severity. The present study was performed in order to investigate whether prolonged treatment with VML 295 up to 8 weeks has a beneficial effect on the overall severity of psoriasis. Moreover, we studied to what extent VML 295 is able to prevent relapse in psoriasis. In the present study, 35 patients with stable chronic plaque psoriasis were included. A representative plaque of at least 16 cm2 was initially treated with clobetasol-17-propionate lotion under hydrocolloid occlusion in all patients. Clearance was achieved within 6 weeks in 31 patients. After clearance, the patients were randomized to treatment and received oral VML 295 capsules 200 mg twice daily or placebo for 8 weeks. Twenty-five patients completed the study. The psoriasis area and severity index (PASI) was assessed before treatment, at clearance, and on days 15, 29, 43 and 5 7 of the treatment period. Biopsies were taken from the treated lesion before treatment, after clearance and at relapse, and cells were analysed by flow cytometry with markers for differentiation (keratin 10), inflammation (vimentin), and proliferation (DNA content). After 8 weeks of treatment, 14 of 15 VML 295-treated patients had relapsed and 11 of 16 placebo-treated patients had relapsed. A total of six patients were withdrawn. The time to relapse and the number of relapsed patients was not significantly different comparing the treatment groups. There was no significant difference in PASI scores between VML 295-treated patients and placebo-treated patients after 8 weeks of treatment. Flow cytometric parameters for differentiation, inflammation and proliferation did not show significant differences between VML 295- and placebo-treated patients. We conclude that oral VML 295 (LY-293111) is not effective in preventing relapse in psoriasis, either clinically or at the cellular level, and that in our group of patients VML 295 had no beneficial effect on overall psoriasis severity. Moreover, we conclude that further development of LTB4 modulating drugs for the treatment of psoriasis is not indicated.

Coexpression of keratins 13 and 16 in human keratinocytes indicates association between hyperproliferation-associated and retinoid-induced differentiation.

In human skin, epidermal differentiation occurs in two ways: normal differentiation, characterized by keratin 10 expression, and alternative differentiation. Alternative differentiation can be hyperproliferation-associated differentiation (expression of keratin 16) or the reinduction of an embryonic type of differentiation (expression of keratin 13). This embryonic type of differentiation is also seen following treatment with retinoids. In the present study, the hypothesis that hyperproliferation-associated and retinoid-induced differentiation are separate processes was investigated. Two areas of normal skin were treated for 24 h with 0. 1% all-trans-retinoic acid. Subsequently, one of the areas was tape-stripped and treatment was continued for 48 h. Multiparameter flow cytometry permitted simultaneous measurement of two coexpressed differentiation markers (retinoid-induced and normal differentiation or retinoid-induced and hyperproliferation-associated differentiation) and the proliferation characteristics (cells in S/G(2)M phase). Concerning normal and retinoid-induced differentiation, the all-trans-retinoic acid-induced expression of keratin 13 was only seen in tape-stripped retinoid-treated skin and exclusively together with that of keratin 10. The assessment of hyperproliferation-associated and retinoid-induced differentiation showed slight expression of keratin 13 without expression of keratin 16 in tape-stripped skin. Coexpression of keratins 16 and 13 was exclusively seen in tape-stripped retinoid-treated skin. The finding that keratin 13 expression following treatment with all-trans-retinoic acid occurred exclusively in hyperproliferative skin suggests that retinoid-induced and hyperproliferation-associated differentiation are coupled. Coexpression of keratins 13 and 16 provides direct experimental evidence for this association.

Novel functional multiparameter flow cytometric assay to characterize proliferation in skin.

Keratins are a group of cytoskeletal proteins that are found in human epidermis and other stratified squamous epithelia. Several different types of keratins have been described. Keratin 10 (K10) is a keratin that is expressed in well differentiated, suprabasal keratinocytes, and keratin 6 (K6) is a keratin which is associated with hyperproliferation. Psoriasis is a chronic inflammatory skin disease, and besides inflammation, disturbed differentiation and hyperproliferation are its hallmarks. In order to study the hyperproliferation associated keratinization in both well differentiated and poorly differentiated keratinocytes, and in order to assess the proliferative activity of all K10 and K6 subpopulations, simultaneous assessment of K6, K10, and DNA content is required. So far, a triple staining protocol had not been available. In the present study, we established a novel protocol for simultaneous measurement of K6, K10, and DNA content, which enables the characterization of the proliferative activity of several cellular subpopulations in epidermis. From 16 patients with psoriasis and from 15 healthy volunteers, punch biopsies were obtained. After preparation of single cell suspensions, cells were stained with the anti-keratin 10 IgG(1)-isotype monoclonal antibody RKSE60, with the anti-keratin 6 IgG(2a)-isotype monoclonal antibody LHK6B, and with the DNA fluorochrome TO-PRO-3 iodide. Isotype specific secondary antibodies conjugated with phycoerythrein (PE) and fluorescein isothiocyanate (FITC) were used as the second step in the staining procedure. Controls were measured omitting the primary antibodies, and gates were set in order to differentiate between the K10 and K6 subpopulations. Samples from both psoriatic patients and healthy volunteers were than measured. Owing to the IgG specificity of RKSE60 and LHK6B, no cross-reactivity was observed between these antibodies. The triple staining with RKSE60, LHK6B, and TO-PRO-3 iodide showed subpopulations of K10 expressing cells, K10/K6 co-expressing cells, and K6 only expressing cells. There was a significant difference in the proportion of K6 expression and K10/K6 co-expression between psoriatic and normal skin. Moreover, the proliferative activity of these subpopulations could be quantified by this protocol. We concluded that a triple staining protocol for the assessment of K6, K10, and DNA content, using the monoclonal antibodies LHK6B, RKSE60, and TO-PRO-3 iodide, supplies reliable and reproducible data for cellular studies on these keratins and for studying the proliferative activity of the subpopulations of these keratins in epidermis. Moreover, the present study showed that with respect to the proportion of K6, significant differences are present between psoriatic and healthy human skin.

The response of distant uninvolved psoriatic skin to standardised injury is not different from that in normal skin.

The epidermis of uninvolved psoriatic skin is characterised by a slight hyperproliferation and an increase in inflammatory parameters, whereas no differentiation abnormalities are seen. Data with respect to the response of distant uninvolved psoriatic skin to standardised injury are not uniform. In this study, a recently developed multiparameter flow cytometric assay was used to compare the response to tape stripping of uninvolved psoriatic and normal skin. With this method, a parameter for proliferation, differentiation and inflammation was measured simultaneously. Concerning these parameters, no statistically significant differences were found between uninvolved psoriatic skin and normal skin. The mechanism that underlies hyperproliferation in distant uninvolved psoriatic skin does not indicate an intrinsic abnormality in keratinocytes. Inflammatory signals might play a role in this process.