Cynomolgus monkey model of interleukin‐31‐induced scratching depicts blockade of human interleukin‐31 receptor A by a humanized monoclonal antibody

Scratching is an important factor exacerbating skin lesions through the so‐called itch‐scratch cycle in atopic dermatitis (AD). In mice, interleukin (IL)‐31 and its receptor IL‐31 receptor A (IL‐31RA) are known to play a critical role in pruritus and the pathogenesis of AD; however, study of their precise roles in primates is hindered by the low sequence homologies between primates and mice and the lack of direct evidence of itch sensation by IL‐31 in primates. We showed that administration of cynomolgus IL‐31 induces transient scratching behaviour in cynomolgus monkeys and by that were able to establish a monkey model of scratching. We then showed that a single subcutaneous injection of 1 mg/kg nemolizumab, a humanized anti‐human IL‐31RA monoclonal antibody that also neutralizes cynomolgus IL‐31 signalling and shows a good pharmacokinetic profile in cynomolgus monkeys, suppressed the IL‐31‐induced scratching for about 2 months. These results suggest that the IL‐31 axis and IL‐31RA axis play as critical a role in the induction of scratching in primates as in mice and that the blockade of IL‐31 signalling by an anti‐human IL‐31RA antibody is a promising therapeutic approach for treatment of AD. Nemolizumab is currently under investigation in clinical trials.     

Repeated administration of IL‐31 upregulates IL‐31 receptor A (IL‐31RA) in dorsal root ganglia and causes severe itch‐associated scratching behaviour in mice

We investigated the effects of repeated administration of interleukin‐31 (IL‐31) on itch‐associated scratching counts (long‐lasting scratching, LLS) and IL‐31‐related receptor mRNA expression in mice. Intra‐dermal (i.d.) injection of IL‐31 (100 and 300 ng/site) every 12 h for 3 days significantly increased LLS. Repeated administration of IL‐31 also increased the expression of IL‐31 receptor A (IL‐31RA) and oncostatin M receptor beta (OSMRβ) in dorsal root ganglia (DRG). After the repeated administration of IL‐31 was discontinued, IL‐31RA expression decreased and reached the baseline level 2 days after the last dose of IL‐31. LLS changed along with DRG IL‐31RA expression. Moreover, IL‐31‐induced IL‐31RA protein expression was confirmed by Western blotting analysis. These data suggest that IL‐31 upregulates IL‐31RA expression in DRG neuron cell bodies, and cutaneous‐injected IL‐31‐induced itching is enhanced by DRG IL‐31RA expression in mice.     

Interleukin‐4 and interleukin‐13 evoke scratching behaviour in mice

Persistent and relapsing itch commonly manifests in inflammatory skin disorders such as atopic dermatitis (AD). AD pathogenesis is driven by interleukin‐4 (IL‐4) and interleukin‐13 (IL‐13). Dupilumab, a monoclonal antibody blocking the action of IL‐4 and IL‐13 effectively reduces the symptoms of AD and itch. Little is known whether IL‐4 and IL‐13 directly contribute to itch transduction. A recently published study (Oetjen et al, Cell, 2017, 171, 217) found IL‐4 and IL‐13 to directly activate itch‐sensory neurons in vitro. Surprisingly, they found no significant increase in scratching after intradermally injecting high doses (2.5 ug/ml) of IL‐4 and IL‐13 into mice. Similar experiments in our lab, however, suggested that both IL‐4 and IL‐13 contribute to acute itch in vivo. We intradermally injected lower doses (1 ug/ml) of IL‐4 and IL‐13 into mice and found a significant increase of scratching bouts compared to vehicle. Interestingly, the combined treatment of IL‐4 and IL‐13 produced additive increase of scratching and acute pruritus at an earlier time point compared to each cytokine administered alone. In summary, our study shows a rapid and significant increase of scratching after intradermal injection of IL‐4, IL‐13 or combined IL‐4/ IL‐13 compared to vehicle in mice 5‐10 minutes after injection. Our data suggest that IL‐4 and IL‐13 alone and combined directly act as potent acute pruritogens on sensory nerves. This finding expands our understanding of cytokines as pruritogens, how targeted anticytokine medications act in AD, and about neuroimmune communication in the skin.     

Epidermal growth factor receptor tyrosine kinase inhibitors induce CCL2 and CCL5 via reduction in IL‐1R2 in keratinocytes

Please cite this paper as: Epidermal growth factor receptor tyrosine kinase inhibitors induce CCL2 and CCL5 via reduction in IL‐1R2 in keratinocytes. Experimental Dermatology 2010; 19 : 730–735. Abstract: Epidermal growth factor receptor tyrosine kinase (EGFR‐TK) is a transducer of mitogenic signals, and is involved in the pathogenesis and progression of a number of cancers, including non‐small cell lung cancer (NSCLC). Gefitinib is an EGFR‐TK inhibitor that is clinically used to treat NSCLC; however, this drug frequently causes adverse effects, including skin eruptions. The mechanism underlying these skin reactions is elusive, although it is assumed that they are caused by the inhibition of EGFR‐TK signalling in epidermal and adnexal cells. In this article, we demonstrate by immunocytochemistry that the skin lesions of patients treated with oral gefitinib had higher expression of CCL2 and CCL5 compared to normal human epidermis. Further, PD153035, a gefitinib prototype, induced CCL2 and CCL5 mRNA and protein expression in HaCaT and HSC‐1 keratinocyte cell lines with or without interleukin‐1 (IL‐1) treatment in vitro. PD153035 also reduced the levels of interleukin‐1 receptor 2 (IL‐1R2), an IL‐1 decoy receptor. Moreover, we demonstrate that reduction in IL‐1R2 by RNA interference increased IL‐1‐mediated CCL2 and CCL5 mRNA and protein expression. Taken together, our data strongly suggest that IL‐1‐mediated signalling is activated to induce the high expression of CCL2 and CCL5 via reduction in IL‐1R2 in the skin lesions caused by gefitinib.     

Possible roles of basophils in chronic itch

Basophils are blood granulocytes and normally constitute <1% of blood peripheral leucocytes. Basophils share some morphological and functional similarities with mast cells, and basophils were once regarded as redundant and negligible circulating mast cells. However, recent studies reveal the indispensable roles of basophils in various diseases, including allergic and pruritic diseases. Basophils may be involved in itch through the mediation of a Th2 immune response, interaction with other cells in the skin and secretion of a wide variety of itch‐related mediators, for example histamine, cytokines and chemokines (IL‐4, IL‐13, IL‐31 and TSLP), proteases (cathepsin S), prostaglandins (PGE2 and PGD2), substance P and platelet‐activating factor. Not only pruritic skin diseases (eg, atopic dermatitis, irritant contact dermatitis, chronic urticaria, prurigo, papulo‐erythroderma of Ofuji, eosinophilic pustular folliculitis, scabies, tick bites and bullous pemphigoid) but also pruritic systemic diseases (eg, primary sclerosing cholangitis and polycythemia vera) may be affected by basophils.     

Gene expression study of IL10 family genes in vitiligo skin biopsies, peripheral blood mononuclear cells and sera

Background Vitiligo is a pigmentation disorder, the cause of which is complex and not yet fully understood. There is a significant change of epidermal cytokines in involved skin of patients with vitiligo compared with uninvolved skin and skin of healthy controls, thus suggesting a possible involvement of cytokines in the pathogenesis of vitiligo. Objectives To evaluate potential roles of IL10 family cytokines (IL10, IL19, IL20, IL22 and IL24) in vitiligo. Along with the selected cytokines, we investigated subunits of the receptors (IL10RA, IL10RB, IL20RA and IL22RA1) which are involved in the signalling pathway of the cytokines. Methods Quantitative real‐time polymerase chain reaction was used to detect mRNA expression levels in samples extracted from skin biopsies and peripheral blood mononuclear cells and an enzyme‐linked immunosorbent assay was used to measure protein concentrations in serum from patients with vitiligo and healthy controls. Results IL22 is significantly associated with vitiligo, especially with the active stage of vitiligo, as shown by results of mRNA expression and supported by results of protein level in sera. IL22 may provoke inflammation which leads to destruction of melanocytes. Conclusions The actual role of IL22 during pathogenesis of vitiligo remains to be better characterized. Signal transductions of other investigated cytokines seem to be regulated on the expression level of their receptor complex subunits.     

Inflammatory mediators causing cutaneous chronic itch in some diseases via transient receptor potential channel subfamily V member 1 and subfamily A member 1

Chronic itch with an itch–scratch vicious circle is a significant problem in a large amount of diseases. Some of these diseases, such as psoriasis, atopic dermatitis, prurigo nodularis, Sézary syndrome, uremic pruritus, diabetes and jaundice, are common. For a very long time, chronic itch has been a thorny problem with few effective treatments. Because of this, itch researchers and dermatologists seek to find the mechanisms among chronic itch, inflammatory cytokines and neurons. As an immediate area of research focus, we are going to find the peripheral cross‐talk between neurons and skin cells. Two receptors, named transient receptor potential channel vanilloid 1 and transient receptor potential channel ankyrin transmembrane protein 1, have been shown to play important roles in chronic itch. Many advances have been made so far this decade. This review talks about the updated mechanism of itch‐related inflammatory cytokines via transient receptor potential channels in cutaneous chronic itch and corresponding diseases. The search for itch‐related inflammatory mediators and the structure of transient receptor potential channels this decade could deepen our understanding of the mechanism of itch and help us find more treatments of chronic itch in the future.     

Increased expression of IL‐33 in rosacea skin and UVB‐irradiated and LL‐37‐treated HaCaT cells

Rosacea is one of the most common dermatoses of adults. Although the detailed pathophysiology remains unknown, it is thought that rosacea is caused by a consistently aberrant, innate immune response, and that LL‐37 plays an important role. However, involvement of the inflammatory cytokine IL‐33 has not yet been studied. We explored the role played by IL‐33 in the pathophysiology of rosacea. First, we immunohistochemically evaluated the expression of IL‐33 and its receptor (ST2) in rosacea skin. Second, we exposed HaCaT cells to ultraviolet B (UVB) irradiation in the presence or absence of LL‐37 and measured the expression of proinflammatory cytokines including IL‐33. We also analysed VEGF (vascular endothelial growth factor) mRNA expression and protein release after costimulation of HaCaT cells by LL‐37 and IL‐33. Immunohistochemically, IL‐33 expression was enhanced in the skin of rosacea patients, especially with erythematotelangiectatic subtype. In vitro, UVB and LL‐37 synergistically increased mRNAs expression of proinflammatory cytokines, especially IL‐33 and IL‐1β. IL‐33 protein release was also synergistically increased by LL‐37 and UVB treatment. LL‐37 and IL‐33 stimulated VEGF mRNA expression and VEGF release from HaCaT cells. Our findings suggest that rosacea skin with abundant LL‐37 may robustly produce and release IL‐33 when exposed to UV radiation. IL‐33 may participate in the angiogenesis and vasodilation of rosacea skin by enhancing VEGF release.     

Evidence on the direct correlation between miR‐31 and IL‐22 axis in IMQ‐induced psoriasis

Psoriatic skin is characterized by a deregulated profile of miRNAs that are contributing in disease development. In this study, we focus on miR‐31, one of the upregulated miRNAs known to promote keratinocytes proliferation and migration. Moreover, miR‐31 expression induction was dependent on a large panel of cytokines including IL‐22. Here, we aimed at investigating the relationship between miR‐31‐5p and IL‐22 axis; and by searching novel molecular target for miR‐31‐5p in keratinocytes. Our data identify a direct correlation between miR‐31‐5p and IL‐22 in psoriasis with Pwp1 as new potential target. These findings confirm the important role of miR‐31 in psoriasis onset and provide a basis for further investigations in miRNAs field in context of skin diseases.     

Understanding the immune landscape in atopic dermatitis: The era of biologics and emerging therapeutic approaches

Atopic dermatitis (AD) is a chronic, systemic, inflammatory disease that affects the skin and is characterized by persistent itch and marked redness. AD is associated with an increased risk of skin infections and a reduced quality of life. Most AD treatment options to date were not designed to selectively target disease‐causing pathways that have been established for this indication. Topical therapies have limited efficacy in moderate‐to‐severe disease, and systemic agents such as corticosteroids and immunosuppressants present with tolerability issues. Advances in the understanding of AD pathobiology have made possible a new generation of more disease‐specific AD therapies. AD is characterized by the inappropriate activation of type 2 T helper (Th2) cells and type 2 innate lymphoid (ILC2) cells, with a predominant increase in type 2 cytokines in the skin, including interleukin (IL)‐13 and IL‐4. Both cytokines are implicated in tissue inflammation and epidermal barrier dysfunction, and monoclonal antibodies targeting each of these interleukins or their receptors are in clinical development in AD. In March 2017, dupilumab, a human anti–IL‐4Rα antibody, became the first biologic to receive approval in the United States for the treatment of moderate‐to‐severe AD. The anti–IL‐13 monoclonal antibodies lebrikizumab and tralokinumab, which bind different IL‐13 epitopes with potentially different effects, are currently in advanced‐stage trials. Here, we briefly review the underlying pathobiology of AD, the scientific basis for current AD targets, and summarize current clinical studies of these agents, including new research to develop both predictive and response biomarkers to further advance AD therapy in the era of precision medicine.     

IL‐36 receptor antagonistic antibodies inhibit inflammatory responses in preclinical models of psoriasiform dermatitis

Psoriasis vulgaris (PV) results from activation of IL‐23/Th17 immune pathway and is further amplified by cytokines/chemokines from skin cells. Among skin‐derived pro‐inflammatory cytokines, IL‐36 family members are highly upregulated in PV patients and play a critical role in general pustular psoriasis. However, there is limited data showing crosstalk between the IL‐23 and IL‐36 pathways in PV. Herein, potential attenuation of skin inflammation in the IL‐23‐induced mouse model of psoriasiform dermatitis by functional inhibition of IL‐36 receptor (IL‐36R) was interrogated. Anti‐mouse IL‐36R monoclonal antibodies (mAbs) were generated and validated in vitro by inhibiting IL‐36α‐induced secretion of CXCL1 from NIH 3T3 cells. Antibody target engagement was demonstrated by inhibition of CXCL1 production in a novel acute model of IL‐36α systemic injection in mice. In addition, anti‐IL‐36R mAbs inhibited tissue inflammation and inflammatory gene expression in an IL‐36α ear injection model of psoriasiform dermatitis demonstrating engagement of the target in the ear skin. To elucidate the possible role of IL‐36 signalling in IL‐23/Th17 pathway, the ability of anti‐IL‐36R mAbs to inhibit skin inflammation in an IL‐23 ear injection model was assessed. Inhibiting the IL‐36 pathway resulted in significant attenuation of skin thickening and psoriasis‐relevant gene expression. Taken together, these data suggest a role for IL‐36 signalling in the IL‐23/Th17 signalling axis in PV.     

IL‐36γ has proinflammatory effects on human endothelial cells

Interleukin‐36 cytokines are predominantly expressed by epithelial cells. Significant upregulation of epidermal IL‐36 is now a recognised characteristic of psoriatic skin inflammation. IL‐36 is known to induce inflammatory responses in dendritic cells, fibroblasts and epithelial cells. Although vascular alterations are a hallmark of psoriatic lesions and dermal endothelial cells are well known to play a critical role in skin inflammation, the effects of IL‐36 on endothelial cells are unexplored. We here show that endothelial cells including dermal microvascular cells express a functionally active IL‐36 receptor. Adhesion molecules VCAM‐1 and ICAM‐1 are upregulated by IL‐36γ stimulation, and this is reversed by the presence of the endogenous IL‐36 receptor antagonist. IL‐36γ‐stimulated endothelial cells secrete the proinflammatory chemokines IL‐8, CCL2 and CCL20. Chemotaxis assays showed increased migration of T‐cells following IL‐36γ stimulation of endothelial cells. These results suggest a role for IL‐36γ in the dermal vascular compartment, and it is likely to enhance psoriatic skin inflammation by activating endothelial cells and promoting leucocyte recruitment.     

Subcutaneous administration of polymerized type I collagen downregulates interleukin (IL)-17A, IL-22 and transforming growth factor-β1 expression, and increases Foxp3-expressing cells in localized scleroderma

Background. Localized scleroderma (LS) is a disfiguring inflammatory autoimmune disease of the skin and underlying tissue. As in systemic sclerosis, a key feature is the presence of T cells in inflammatory lesions. Aim. To evaluate the effect of polymerized type I collagen vs. methylprednisolone (MP) in LS, and to determine the influence of this polymerized collagen (PC) on CD4+ peripheral T cells expressing interleukin (IL)‐4, IL‐17A, interferon‐γ and Forkhead box protein (Foxp)3, and on cells expressing transforming growth factor (TGF)‐β1, IL‐17A, IL‐22 and Foxp3 in the skin. Methods. In total, 16 patients with LS were treated for 3 months with monthly subcutaneous intralesional injections of 0.1 mL MP (giving a total dose of 20 mg/mL each month) and 15 patients were treated, with weekly subcutaneous intralesional injections of PC, ranging from 0.2 mL (equivalent to 1.66 mg collagen) for a lesion of 50 mm in size, up to a maximum of 1.0 mL (8.3 mg collagen) for a lesion > 100 mm in size, and followed up for a further 6 months. Skin biopsies were obtained from lesions at baseline (before treatment) and 9 months later (6 months after treatment end). Tissue sections were evaluated by histology and immunohistochemistry (IL‐17A, IL‐22, TGF‐β1 and Foxp3). CD4+ T‐cell subsets were determined in peripheral blood by flow cytometry. Results. Abnormal tissue architecture was seen in the biopsies taken from patients treated with MP, whereas the PC treatment restored normal skin architecture. PC downregulated pro‐inflammatory/profibrotic cytokine expression in peripheral cells, and upregulated the number of regulatory T cells (Tregs) in skin. PC was safe and well tolerated. Conclusions. PC is not only an antifibrotic/fibrolytic agent but also an immunomodulator biodrug that restores the balance between T helper (Th)1, Th2, Th17 and Tregs, downregulates production of pro‐inflammatory or profibrogenic cytokines (IL‐17A, IL‐22 and TGF‐β1), and renews skin architecture, without adverse effects.     

Biologics for psoriasis: What is new?

Etiology of psoriasis is unclear but environmental, genetic, and immune factors act significant roles in the pathogenesis of this disease. Helper T cells (TH), plasmoid, and dermal dendritic cells play a prominent role in the development of classical psoriatic lesions. Interleukin stimulation is another important process in the pathogenesis of the disease that directly influences keratinocytes and leading to the formation of psoriatic pattern in the skin. Tumor necrosis factor (TNF) α which releases from keratinocytes activates dendritic cells in the early stages of complex pathogenesis of psoriasis. Activated keratinocytes also produce other proinflammatory cytokines (IL‐1b and IL‐6), antimicrobial peptides, and various chemokines. TNF activates dendritic cells that produce IL‐23, leading to TH17 differentiation. TH17 cells secrete IL‐17A, which has been shown to promote psoriatic skin changes. Consequently, after clarification of these main pathological mechanisms, anti‐IL therapies have been accepted as a major treatment for patients with moderate‐to‐severe psoriasis. Here, actual information will be presented about biological agents currently in clinical use or being tested for clinical application for treatment of patients with psoriasis.     

NLRP3炎性小体与皮肤病

【摘要】 NLRP3炎性小体在固有免疫中发挥重要作用，通过活化胱天蛋白酶1诱导细胞因子白细胞介素（IL）-1β和IL-18的成熟和释放，参与多种宿主免疫和炎性反应。一旦机体对NLRP3炎性小体的调控失衡，则可能产生过量的IL-1β和IL-18，从而引发一系列炎症性疾病。NLRP3炎性小体活化在痤疮、银屑病、坏疽性脓皮病、多发性肌炎/皮肌炎、大疱性类天疱疮等皮肤病中发挥重要作用。本文综述NLRP3炎性小体在皮肤病中的研究进展。