Psoriasis is a chronic inflammatory disease characterised by sharply demarcated erythematous and scaly skin lesions accompanied by systemic manifestations. Classified by WHO as one of the most ...serious non-infectious diseases, psoriasis affects 2–3% of the global population. Mechanistically, psoriatic lesions result from hyperproliferation and disturbed differentiation of epidermal keratinocytes that are provoked by immune mediators of the IL-23 and IL-17 pathway. Translational immunology has had impressive success in understanding and controlling psoriasis. Psoriasis is the first disease to have been successfully treated with therapeutics that directly block the action of the cytokines of this pathway; in fact, therapeutics that specifically target IL-23, IL-17, and IL-17RA are approved for clinical use and show excellent efficacy. Furthermore, inhibitors of IL-23 and IL-17 intracellular signalling, such as TYK2 or RORγt, are in clinical development. Although therapies that target the IL-23 and IL-17 pathway also improve psoriatic arthritis symptoms, their effects on long-term disease modification and psoriasis-associated comorbidities still need to be explored.
Accumulating data on cellular and molecular pathways help to develop novel therapeutic strategies in skin inflammation and autoimmunity. Examples are psoriasis and atopic dermatitis, two clinically ...and immunologically well-defined disorders. Here, the elucidation of key pathogenic factors such as IL-17A/IL-23 on the one hand and IL-4/IL-13 on the other hand profoundly changed our therapeutic practice. The knowledge on intracellular pathways and governing factors is shifting our attention to new druggable molecules. Multiple cytokine receptors signal through Janus kinases (JAKs) and associated signal transducer and activators of transcription (STATs). Inhibition of JAKs can simultaneously block the function of multiple cytokines. Therefore, JAK inhibitors (JAKi) are emerging as a new class of drugs, which in dermatology can either be used systemically as oral drugs or locally in topical formulations. Inhibition of JAKs has been shown to be effective in various skin disorders. The first oral JAKi have been recently approved for the treatment of rheumatoid arthritis and psoriatic arthritis. Currently, multiple inhibitors of the JAK/STAT pathway are being investigated for skin diseases like alopecia areata, atopic dermatitis, dermatomyositis, graft-versus-host-disease, hidradenitis suppurativa, lichen planus, lupus erythematosus, psoriasis, and vitiligo. Here, we aim to discuss the immunological basis and current stage of development of JAKi in dermatology.
Psoriasis is an inflammatory skin disease with strong neutrophil (PMN) infiltration and high levels of the antimicrobial peptide, LL37. LL37 in complex with DNA and RNA is thought to initiate disease ...exacerbation via plasmacytoid dendritic cells. However, the source of nucleic acids supposed to start this initial inflammatory event remains unknown. We show here that primary murine and human PMNs mount a fulminant and self-propagating neutrophil extracellular trap (NET) and cytokine response, but independently of the canonical NET component, DNA. Unexpectedly, RNA, which is abundant in NETs and psoriatic but not healthy skin, in complex with LL37 triggered TLR8/TLR13-mediated cytokine and NET release by PMNs in vitro and in vivo. Transfer of NETs to naive human PMNs prompts additional NET release, promoting further inflammation. Our study thus uncovers a self-propagating vicious cycle contributing to chronic inflammation in psoriasis, and NET-associated RNA (naRNA) as a physiologically relevant NET component.
Janus kinases in immune cell signaling Ghoreschi, Kamran; Laurence, Arian; O'Shea, John J
Immunological reviews,
March 2009, Letnik:
228, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Janus family kinases (Jaks), Jak1, Jak2, Jak3, and Tyk2, form one subgroup of the non-receptor protein tyrosine kinases. They are involved in cell growth, survival, development, and ...differentiation of a variety of cells but are critically important for immune cells and hematopoietic cells. Data from experimental mice and clinical observations have unraveled multiple signaling events mediated by Jaks in innate and adaptive immunity. Deficiency of Jak3 or Tyk2 results in defined clinical disorders, which are also evident in mouse models. A striking phenotype associated with inactivating Jak3 mutations is severe combined immunodeficiency syndrome, whereas mutation of Tyk2 results in another primary immunodeficiency termed autosomal recessive hyperimmunoglobulin E syndrome. By contrast, complete deletion of Jak1 or Jak2 in the mouse are not compatible with life and, unsurprisingly, do not have counterparts in human disease. However, activating mutations of each of the Jaks are found in association with malignant transformation, the most common being gain-of-function mutations of Jak2 in polycythemia vera and other myeloproliferative disorders. Our existing knowledge on Jak signaling pathways and fundamental work on their biochemical structure and intracellular interactions allow us to develop new strategies for controlling autoimmune diseases or malignancies by developing selective Jak inhibitors, which are now coming into clinical use. Despite the fact that Jaks were discovered only a little more than a decade ago, at the time of writing there are 20 clinical trials underway testing the safety and efficacy of Jak inhibitors.
Interleukin 17A (IL-17A) is one of the currently known six members of the IL-17 cytokine family and is implicated in immune responses to infectious pathogens and in the pathogenesis of inflammatory ...autoimmune diseases like psoriasis. Psoriatic skin is characterized by high expression of IL-17A and IL-17F, which act on immune and non-immune cell types and strongly contribute to tissue inflammation. In psoriatic lesions, IL-17A, IL-17E, and IL-17F are involved in neutrophil accumulation, followed by the formation of epidermal micro abscesses. IL-17A together with other Th17 cytokines also upregulates the production of several chemokines that are implicated in psoriasis pathogenesis. IL17A-targeting antibodies show an impressive clinical efficacy in patients with psoriasis. Studies have reported an improvement of at least 75% as measured by the psoriasis area and severity index (PASI) in >80% of patients treated with anti-IL-17A therapy. Psoriasis skin manifestations, cardiovascular as well as metabolic disease in psoriasis appear to share pathogenic mechanisms evolving around IL-17A and its proinflammatory role. Thus, anti-IL-17A therapy not only improves skin manifestations of psoriasis, but also cardiovascular inflammation as well as metabolic factors and different domains of psoriatic arthritis (PsA) including peripheral arthritis, enthesitis, dactylitis, and axial involvement. This review summarizes the biological role of IL-17A, before reviewing currently available data on its role in the physiology and pathophysiology of the skin, as well as the cardiovascular and the metabolic system. In conclusion, clinical recommendations for patients with moderate to severe psoriasis based on the current available data are given.
Fumaric acid esters (FAEs) such as dimethylfumarate (DMF) are used for the treatment of adults with moderate‐to‐severe psoriasis. The mode of action of FAEs is complex. Here, we provide a ...comprehensive review of the literature to describe the molecular mechanisms by which DMF and its active metabolite monomethylfumarate (MMF) exert their anti‐inflammatory and immune modulatory effects. MMF can bind to the hydroxy‐carboxylic acid receptor 2 (HCA2) on the cell surface and both DMF and MMF react with intracellular glutathione following cell penetration. DMF and to some extent also MMF modulate the activity of certain cellular signalling proteins such as the nuclear factor (erythroid‐derived 2)‐like 2 (Nrf2), nuclear factor kappa B (Nf‐κB) and the cellular concentration of cyclic adenosine monophosphate. Some studies show that DMF can also affect the hypoxia‐inducible factor 1‐alpha (HIF‐1α). These actions seem to be responsible for i) the downregulation of inflammatory cytokines and ii) an overall shift from a proinflammatory Th1/Th17 response to an anti‐inflammatory/regulatory Th2 response. Both steps are necessary for the amelioration of psoriatic inflammation, although additional mechanisms have been proposed. There is a growing body of evidence to support the notion that DMF/MMF may also exert effects on granulocytes and non‐immune cell lineages including keratinocytes and endothelial cells. A better understanding of the multiple molecular mechanisms involved in the cellular action of FAEs will help to adapt and further improve the use of such small molecules for the treatment of psoriasis and other chronic inflammatory diseases.
Angiogenesis drives psoriasis pathogenesis Heidenreich, Regina; Röcken, Martin; Ghoreschi, Kamran
International journal of experimental pathology,
June 2009, Letnik:
90, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Summary
Psoriasis pathogenesis is closely associated with disease‐inducing Th1 and Th17 cells. Yet, several studies suggest that aberrant keratinocyte or endothelial cell signalling significantly ...contributes to disease manifestation. Histological hallmarks of psoriatic skin include the infiltration of multiple immune cells, keratinocyte proliferation and increased dermal vascularity. Formation of new blood vessels starts with early psoriatic changes and disappears with disease clearance. Several angiogenic mediators like vascular endothelial growth factor, hypoxia‐inducible factors, angiopoietins and pro‐angiogenic cytokines, such as tumour necrosis factor (TNF), interleukin (IL)‐8 and IL‐17, are up‐regulated in psoriasis development. Contact‐ and mediator‐dependent factors derived from keratinocytes, mast cells and immune cells may contribute to the strong blood vessel formation of psoriasis. New technologies and experimental models provide new insights into the role of angiogenesis in psoriasis pathogenesis. Interestingly, many therapies target not only immune cells, but also protein structures of endothelial cells. Here we summarize the role of pro‐angiogenic factors in psoriasis development and discuss angiogenesis as a potential target of novel therapies.
Lichen planus – a clinical guide Solimani, Farzan; Forchhammer, Stephan; Schloegl, Alexandra ...
Journal der Deutschen Dermatologischen Gesellschaft,
June 2021, 2021-06-00, 20210601, Letnik:
19, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Summary
Lichen planus (LP) is a chronic lichenoid inflammatory disorder of the skin, mucosa and of the appendages. LP is classically characterized by the presence of a rich infiltration of ...inflammatory T cells, which migrate in the upper part of the dermis, arranged in a band‐like pattern. Different sub types of the disease have been so far described. Albeit LP is clinically well defined, the disease still represents a therapeutic enigma. Especially with regard to mucosal or scalp affecting LP types, which often present a recalcitrant and treatment unresponsive course, efficacious therapeutic options are still lacking. Thus, LP represents a disease with a high psychosocial burden. Yet, development in the deciphering of LP pathogenesis reveals possible new druggable targets, thus paving the way for future therapeutic options. In this clinical guide, we summarize the current clinical knowledge and therapeutic standards and discuss the future perspective for the management of LP.
The better understanding of the immunopathogenesis of psoriasis has led to the development of highly efficacious targeted therapies with favorable safety profiles. Among them, the class of ...Interleukin (IL)-17 antibodies are well established for the treatment of psoriasis, psoriatic arthritis and axial spondyloarthritis. Bimekizumab is a new antibody that simultaneously neutralizes IL-17A and IL-17F. We present two patients with psoriasis, who lost response to several biologics, among them IL-17 antagonists such as secukinumab, ixekizumab or brodalumab. Besides plaque-type psoriasis, patients also had psoriasis in hard-to-treat areas such as scalp and groins or psoriatic arthritis. Remarkably, both patients already responded to the therapy with bimekizumab 4 weeks after the first injection and, one year thereafter, both patients sustained PASI100. No side effects were observed. The fast response to bimekizumab emphasizes the crucial role of IL-17F in the pathogenesis of psoriasis. Besides, due to the new mechanism of action, non-responders to other anti-IL-17 therapies could benefit when switched to bimekizumab.
Interleukin 2 (IL-2), a cytokine linked to human autoimmune disease, limits IL-17 production. Here we found that deletion of the gene encoding the transcription factor STAT3 in T cells abrogated ...IL-17 production and attenuated autoimmunity associated with IL-2 deficiency. Whereas STAT3 induced IL-17 and the transcription factor RORγt and inhibited the transcription factor Foxp3, IL-2 inhibited IL-17 independently of Foxp3 and RORγt. STAT3 and STAT5 bound to multiple common sites across the locus encoding IL-17. The induction of STAT5 binding by IL-2 was associated with less binding of STAT3 at these sites and the inhibition of associated active epigenetic marks. 'Titration' of the relative activation of STAT3 and STAT5 modulated the specification of cells to the IL-17-producing helper T cell (T(H)17 cell) subset. Thus, the balance rather than the absolute magnitude of these signals determined the propensity of cells to make a key inflammatory cytokine.
PDF
