Sandra Philipp

Immunopathogenesis of psoriasis

Abstract:  Psoriasis is a chronic skin disease that affects about 1.5% of the Caucasian population and is characterized by typical macroscopic and microscopic skin alterations. Psoriatic lesions are sharply demarcated, red and slightly raised lesions with silver‐whitish scales. The microscopic alterations of psoriatic plaques include an infiltration of immune cells in the dermis and epidermis, a dilatation and an increase in the number of blood vessels in the upper dermis, and a massively thickened epidermis with atypical keratinocyte differentiation. It is considered a fact that the immune system plays an important role in the pathogenesis of psoriasis. Since the early 1990s, it has been assumed that T1 cells play the dominant role in the initiation and maintenance of psoriasis. However, the profound success of anti‐tumor necrosis factor‐α therapy, when compared with T‐cell depletion therapies, should provoke us to critically re‐evaluate the current hypothesis for psoriasis pathogenesis. Recently made discoveries regarding other T‐cell populations such as Th17 and regulatory T cells, dendritic cells, macrophages, the keratinocyte signal transduction and novel cytokines including interleukin (IL)‐22, IL‐23 and IL‐20, let us postulate that the pathogenesis of psoriasis consists of distinct subsequent stages, in each of them different cell types playing a dominant role. Our model helps to explain the varied effectiveness of the currently tested immune modulating therapies and may enable the prediction of the success of future therapies.

IL-22 and IL-20 are key mediators of the epidermal alterations in psoriasis while IL-17 and IFN-γ are not

Psoriasis is a common chronic skin disease with a largely unknown pathogenesis. We demonstrate here that transgenic over-expression of interleukin (IL)-22 in mice resulted in neonatal mortality and psoriasis-like skin alterations including acanthosis and hypogranularity. This cutaneous phenotype may be caused by the direct influence of IL-22 on keratinocytes, since this cytokine did not affect skin fibroblasts, endothelial cells, melanocytes, or adipocytes. The comparison of cytokines with hypothesized roles in psoriasis pathogenesis determined that neither interferon (IFN)-γ nor IL-17, but only IL-22 and, with lower potency, IL-20 caused psoriasis-like morphological changes in a three-dimensional human epidermis model. These changes were associated with inhibited keratinocyte terminal differentiation and with STAT3 upregulation. The IL-22 effect on differentiation-regulating genes was STAT3-dependent. In contrast to IL-22 and IL-20, IFN-γ and IL-17 strongly induced T-cell and neutrophilic granulocyte-attracting chemokines, respectively. Tumor necrosis factor-α potently induced diverse chemokines and additionally enhanced the expression of IL-22 receptor pathway elements and amplified some IL-22 effects. This study suggests that different cytokines are players in the psoriasis pathogenesis although only the IL-10 family members IL-22 and IL-20 directly cause the characteristic epidermal alterations.

S3 – Guidelines on the treatment of psoriasis vulgaris (English version). Update

Psoriasis vulgaris is a common and often chronic inflammatory skin disease. The incidence of psoriasis in Western industrialized countries ranges from 1.5% to 2%. Patients afflicted with severe psoriasis vulgaris may experience a significant reduction in quality of life. Despite the large variety of treatment options available, surveys have shown that patients still do not received optimal treatments. To optimize the treatment of psoriasis in Germany, the Deutsche Dermatologi sche Gesellschaft (DDG) and the Berufsverband Deutscher Dermatologen (BVDD) have initiated a project to develop evidence‐based guidelines for the management of psoriasis. They were first published in 2006 and updated in 2011. The Guidelines focus on induction therapy in cases of mild, moderate and severe plaque‐type psoriasis in adults including systemic therapy, UV therapy and topical therapies.

The Th17 cytokine IL‐22 induces IL‐20 production in keratinocytes: A novel immunological cascade with potential relevance in psoriasis

Psoriasis is a common chronic skin disease. Recent studies demonstrated that IL‐20 and IL‐22, cytokines produced by keratinocytes and T cells, respectively, both inhibit keratinocyte terminal differentiation and induce psoriasis‐like epidermis alterations. Here, we investigated the relationship between these mediators. Although IL‐20 was not able to regulate IL‐22 production, IL‐22 induced IL‐20 mRNA and protein in human keratinocytes. However, IL‐22 had only a minimal effect, if any, on IL‐19 and IL‐26. Cutaneous IL‐20 was also elevated in mice following IL‐22 application. Accordingly, some of IL‐22s effects on differentiation‐regulating genes were partially mediated by an endogenous, secreted protein and attenuated by anti‐IL‐20 Ab. Like IL‐22, IL‐17A and TNF‐α induced IL‐20 in keratinocytes, whereas IFN‐γ and IL‐20 itself did not. Furthermore, IL‐17A and TNF‐α individually strengthened the IL‐22‐induced IL‐20 production. In lesional skin of psoriasis patients, highly elevated IL‐20 levels strongly correlated with IL‐22, and to a lesser extent, with IL‐17A and TNF‐α. As previously shown for IL‐22, IL‐20 blood levels correlated with the disease severity, although with a lower significance. This study demonstrates that a T‐cell mediator induces a tissue cell mediator with similar effects to its own and therefore suggests the existence of a novel type of pathogenetic cascade.

Increased Prevalence of Metabolic Syndrome in Patients with Acne Inversa

Background Acne inversa (AI; also designated as Hidradenitis suppurativa) is a common chronic inflammatory skin disease, localized in the axillary, inguinal and perianal skin areas that causes painful, fistulating sinuses with malodorous purulence and scars. Several chronic inflammatory diseases are associated with the metabolic syndrome and its consequences including arteriosclerosis, coronary heart disease, myocardial infraction, and stroke. So far, the association of AI with systemic metabolic alterations is largely unexplored. Methods and Findings A hospital-based case-control study in 80 AI patients and 100 age- and sex-matched control participants was carried out. The prevalence of central obesity (odds ratio 5.88), hypertriglyceridemia (odds ratio 2.24), hypo-HDL-cholesterolemia (odds ratio 4.56), and hyperglycemia (odds ratio 4.09) in AI patients was significantly higher than in controls. Furthermore, the metabolic syndrome, previously defined as the presence of at least three of the five alterations listed above, was more common in those patients compared to controls (40.0% versus 13.0%; odds ratio 4.46, 95% confidence interval 2.02 to 9.96; P<0.001). AI patients with metabolic syndrome also had more pronounced metabolic alterations than controls with metabolic syndrome. Interestingly, there was no correlation between the severity or duration of the disease and the levels of respective parameters or the number of criteria defining the metabolic syndrome. Rather, the metabolic syndrome was observed in a disproportionately high percentage of young AI patients. Conclusions This study shows for the first time that AI patients have a high prevalence of the metabolic syndrome and all of its criteria. It further suggests that the inflammation present in AI patients does not have a major impact on the development of metabolic alterations. Instead, evidence is given for a role of metabolic alterations in the development of AI. We recommend monitoring of AI patients in order to correct their modifiable cardiovascular risk factors.

Risankizumab versus Ustekinumab for Moderate-to-Severe Plaque Psoriasis

BACKGROUND Interleukin‐23 is thought to be critical to the pathogenesis of psoriasis. We compared risankizumab (BI 655066), a humanized IgG1 monoclonal antibody that inhibits interleukin‐23 by specifically targeting the p19 subunit and thus prevents interleukin‐23 signaling, and ustekinumab, an interleukin‐12 and interleukin‐23 inhibitor, in patients with moderate‐to‐severe plaque psoriasis. METHODS We randomly assigned a total of 166 patients to receive subcutaneous injections of risankizumab (a single 18‐mg dose at week 0 or 90‐mg or 180‐mg doses at weeks 0, 4, and 16) or ustekinumab (45 or 90 mg, according to body weight, at weeks 0, 4, and 16). The primary end point was a 90% or greater reduction from baseline in the Psoriasis Area and Severity Index (PASI) score at week 12. RESULTS At week 12, the percentage of patients with a 90% or greater reduction in the PASI score was 77% (64 of 83 patients) for risankizumab (90‐mg and 180‐mg groups, pooled), as compared with 40% (16 of 40 patients) for ustekinumab (P<0.001); the percentage of patients with a 100% reduction in the PASI score was 45% in the pooled 90‐mg and 180‐mg risankizumab groups, as compared with 18% in the ustekinumab group. Efficacy was generally maintained up to 20 weeks after the final dose of 90 or 180 mg of risankizumab. In the 18‐mg and 90‐mg risankizumab groups and the ustekinumab group, 5 patients (12%), 6 patients (15%), and 3 patients (8%), respectively, had serious adverse events, including two basal‐cell carcinomas and one major cardiovascular adverse event; there were no serious adverse events in the 180‐mg risankizumab group. CONCLUSIONS In this phase 2 trial, selective blockade of interleukin‐23 with risankizumab was associated with clinical responses superior to those associated with ustekinumab. This trial was not large enough or of long enough duration to draw conclusions about safety. (Funded by Boehringer Ingelheim; ClinicalTrials.gov number, NCT02054481).

German S3-guidelines on the treatment of psoriasis vulgaris (short version)

Psoriasis vulgaris is a common and often chronic inflammatory skin disease. The incidence of psoriasis in Western industrialized countries ranges from 1.5 to 2%. Patients afflicted with severe psoriasis vulgaris may experience a significant reduction in quality of life. Despite the large variety of treatment options available, patient surveys have revealed insufficient satisfaction with the efficacy of available treatments and a high rate of medication non-compliance (Richards et al. in J Am Acad Dermatol 41(4):581–583, 1999). To optimize the treatment of psoriasis in Germany, the Deutsche Dermatologische Gesellschaft (DDG) and the Berufsverband Deutscher Dermatologen (BVDD) have initiated a project to develop evidence-based guidelines for the management of psoriasis first published in 2006 and now updated in 2011. The Guidelines focus on induction therapy in cases of mild, moderate, and severe plaque-type psoriasis in adults. This short version of the guidelines presents the resulting series of therapeutic recommendations, which were based on a systematic literature search and discussed and approved by a team of dermatology experts. In addition to the therapeutic recommendations provided in this short version, the full version of the guidelines includes information on contraindications, adverse events, drug interactions, practicality, and costs, as well as detailed information on how best to apply the treatments described (for full version please see Nast et al. in JDDG Suppl 2:S1–S104, 2011 or http://www.psoriasis-leitlinie.de).

Pan-selectin antagonism improves psoriasis manifestation in mice and man

The selectin family of vascular cell adhesion molecules is comprised of structurally related carbohydrate binding proteins, which mediate the initial rolling of leukocytes on the activated vascular endothelium. Because this process is one of the crucial events in initiating and maintaining inflammation, selectins are proposed to be an attractive target for the development of new antiinflammatory therapeutics. Here, we demonstrate that the synthetic pan-selectin antagonist bimosiamose is effective in pre-clinical models of psoriasis as well as in psoriatic patients. In vitro bimosiamose proved to be inhibitory to E- or P-selectin dependent lymphocyte adhesion under flow conditions. Using xenogeneic transplantation models, bimosiamose reduced disease severity as well as development of psoriatic plaques in symptomless psoriatic skin. The administration of bimosiamose in patients suffering from psoriasis resulted in a reduction of epidermal thickness and lymphocyte infiltration. The clinical improvement was statistically significant (P=0.02) as analyzed by comparison of psoriasis area and severity index before and after treatment. Assessment of safety parameters showed no abnormal findings. These data suggest that pan-selectin antagonism may be a promising strategy for the treatment of psoriasis and other inflammatory diseases.

IL-29 Is Produced by TH17 Cells and Mediates the Cutaneous Antiviral Competence in Psoriasis

Psoriasis, but not atopic dermatitis patients, express elevated antiviral proteins in lesional skin because of the TH17 cytokine IL-29. IL-29 Jumps Out of the Skin The skin is the first line of defense against infection. It serves not only as a physical barrier but also, when that barrier is broken, as a battleground for the immune system. But what happens during chronic skin diseases, such as psoriasis and atopic dermatitis (AD)? Although patients with both diseases have continuous impaired skin barrier function, only AD patients frequently suffer from cutaneous viral infection. Wolk et al. now report that psoriatic patients are protected by elevated antiviral proteins (AVPs) that are up-regulated in response to interleukin-29 (IL-29) produced by the adaptive immune system. The authors first compared lesions from AD and psoriatic patients and healthy controls. They found higher amounts of AVPs in the psoriatic lesions. They then compared expression of 30 different cytokines with AVP expression and found that only IL-29 correlated with AVPs. Notably, IL-29 was absent in healthy and AD subjects. Neutralization of IL-29 in psoriatic lesions reduced their AVP expression. The relationship between IL-29 and AVP production was direct because this cytokine increased AVP (but not antibacterial protein) production in multiple models both in vitro and in vivo. What’s more, the IL-29 was secreted by TH17 cells—a proinflammatory immune cell type not previously known to produce IL-29. Together, these results suggest that TH17 cell secretion of IL-29 in psoriatic, but not AD, patients is critical for AVP-mediated viral defense. Psoriasis and atopic dermatitis (AD) are the most common chronic inflammatory skin diseases. Although both patient groups show strongly impaired skin barrier function, only AD patients frequently suffer from cutaneous viral infections. The mechanisms underlying the distinct susceptibilities to these pathogenetic and often life-threatening infections are unknown. We show that antiviral proteins (AVPs) such as MX1, BST2, ISG15, and OAS2 were strongly elevated in psoriatic compared to AD lesions and healthy skin. Of 30 individually quantified cytokines in psoriatic lesions, interleukin-29 (IL-29) was the only mediator whose expression correlated with the AVP levels. IL-29 was absent in AD lesions, and neutralization of IL-29 in psoriatic skin reduced AVP expression. Accordingly, IL-29 raised AVP levels in isolated keratinocytes, epidermis models, and human skin explants, but did not influence antibacterial protein production. AVP induction correlated with increased antiviral defense of IL-29–treated keratinocytes. Furthermore, IL-29 elevated the expression of signaling elements, resulting in increased sensitivity of keratinocytes toward its own action. We identified T helper 17 (TH17) cells as IL-29 producers and demonstrated their ability to increase the antiviral competence of keratinocytes in an IL-29–dependent manner. Transforming growth factor–β and the activity of RORγt/RORα were most critical for the development of IL-29–producing TH17 cells. IL-29 secretion by these cells was dependent on NFAT and c-Jun N-terminal kinase and was inhibited by IL-4. These data suggest that TH17 cell–derived IL-29, which is absent in AD, mediates the robust antiviral state on psoriatic skin, and demonstrate a new function of TH17 cells.

IL-19 Is a Component of the Pathogenetic IL-23/IL-17 Cascade in Psoriasis

Psoriasis is a common chronic inflammatory disease with characteristic skin alterations and functions as a model of immune-mediated disorders. Cytokines have a key role in psoriasis pathogenesis. Here, we demonstrated that out of 30 individually quantified cytokines, IL-19 showed the strongest differential expression between psoriatic lesions and healthy skin. Cutaneous IL-19 overproduction was reflected by elevated IL-19 blood levels that correlated with psoriasis severity. Accordingly, anti-psoriatic therapies substantially reduced both cutaneous and systemic IL-19 levels. IL-19 production was induced in keratinocytes by IL-17A and was further amplified by tumor necrosis factor-α and IL-22. Among skin cells, keratinocytes were found to be important targets of IL-19. IL-19 alone, however, regulated only a few keratinocyte functions. While increasing the production of S100A7/8/9 and, to a moderate extent, also IL-1β, IL-20, chemokine C-X-C motif ligand 8, and matrix metalloproteinase 1, IL-19 had no clear influence on the differentiation, proliferation, or migration of these cells. Importantly, IL-19 amplified many IL-17A effects on keratinocytes, including the induction of β-defensins, IL-19, IL-23p19, and T helper type 17-cell- and neutrophil-attracting chemokines. In summary, IL-19 as a component of the IL-23/IL-17 axis strengthens the IL-17A action and might be a biomarker for the activity of this axis in chronic inflammatory disorders.