Yoshiko Sakaguchi

Skin-specific expression of IL-33 activates group 2 innate lymphoid cells and elicits atopic dermatitis-like inflammation in mice

Transgenic mice expressing the mouse interleukin 33 (IL-33) gene driven by a keratin 14 promoter were generated. The skin-selective expression of the IL-33 gene was enhanced, and intense immunofluorescence for IL-33 was evident in the nuclei of the epidermis. Spontaneous itchy dermatitis developed in those mice at 6–8 wk of age in specific pathogen-free conditions. In the lesional skin, the epidermis was thickened and the eosinophils were infiltrated with increased expression of the eosinophil peroxidase and major basic protein genes. Mast cells were also abundant there, and blood histamine and total IgE levels were high. Those phenotypes closely resemble the features of atopic dermatitis. In peripheral blood and lesional skin, IL-5, IL-13, regulated upon activation, normally T-expressed, and presumably secreted (RANTES)/CCL5, and Eotaxin 1/CCL11 were increased, whereas TNF-α, IFN-γ, and thymic stromal lymphopoietin (TSLP) were unaltered. Furthermore, the proportion of group 2 innate lymphoid cells (ILC2s), which produce IL-5, were significantly increased in the lesional skin, peripheral blood, and regional lymph nodes. The dermatitis with eosinophil infiltration was improved by the administration of an anti-IL-5 antibody. These results suggest that the expression of IL-33 in the skin activates an immune response involving ILC2 and that this process might play a crucial role in the pathogenesis of allergic inflammation that is characteristic of atopic dermatitis.

Serum cytokines correlated with the disease severity of generalized pustular psoriasis

To characterize serum biomarkers reflecting the severity of generalized pustular psoriasis (GPP), we measured multiple cytokine/chemokine levels in 39 serum samples from 6 cases with GPP during the course of the disease. Serum levels of IL-4, IL-8, CXCL1 and CCL3 were positively correlated with the severity scores of GPP, white blood cell counts and serum C-reactive protein levels. Serum levels of IL-1β, IL-1ra, IL-6, IL-10, IL-12p70, IL-18, IL-22, IFN-γ and VEGF showed strong positive correlations (r > 0.4, p < 0.01) with all those 3 clinical markers. Of those, IL-10 and IL-22 were significantly decreased after treatment in parallel with the GPP score and therefore those two serum cytokines might be useful to evaluate the efficacy of treatment for GPP.

Interleukin-17- and protease-activated receptor 2-mediated production of CXCL1 and CXCL8 modulated by cyclosporine A, vitamin D3 and glucocorticoids in human keratinocytes

Protease‐activated receptor 2 (PAR2) is a G protein‐coupled receptor which mediates a variety of functions in the skin including cutaneous inflammation. SLIGKV‐NH2, an agonist peptide for PAR2, enhanced the interleukin (IL)‐17‐induced production of two CXC chemokines, CXCL1 (GRO‐α) and CXCL8 (IL‐8), in normal human epidermal keratinocytes (NHEK) in a concentration‐dependent manner. The enhanced production of those chemokines was suppressed by a PAR2‐specific siRNA. The SLIGKV‐NH2‐induced production of both CXCL1 and CXCL8 was markedly reduced by cyclosporine A. The enhanced production of CXCL1 was suppressed by 1α, 24R‐dihydroxyvitamin D3, an active form of vitamin D3, and weakly by glucocorticoids, dexamethasone and clobetasol propionate, whereas production of CXCL8 was not altered by any of those receptor agonists. In psoriatic skin, the thickened upper spinous layer of the epidermis was positive for PAR2 protein and the expression of the IL17A mRNA was increased. These results suggest that the IL‐17‐induced pro‐inflammatory reaction is enhanced by the activation of PAR2 in keratinocytes, and that the effect of PAR2 is differentially modulated by cyclosporine A, the active form of vitamin D3 and glucocorticoids.

Knocking-in the R142C mutation in transglutaminase 1 disrupts the stratum corneum barrier and postnatal survival of mice.

BACKGROUND Mutations in the gene encoding transglutaminase 1 (TG1) are responsible for various types of autosomal recessive congenital ichthyosis (ARCI), such as lamellar ichthyosis (LI), congenital ichthyosiform erythroderma (CIE) and some minor variants of ARCI. A point mutation of R143C in the β-sandwich domain of TG1 has been often identified in patients with LI or CIE. OBJECTIVE To elucidate the effect of that point mutation on skin barrier structures and functions, we generated mice with a point mutation of R142C, which corresponds to the R143C mutation in human TG1. METHODS A mouse line with the R142C point mutation in TG1 was established using a gene targeting technique and the Cre-loxP system. The skin phenotypes were analyzed in homozygous mutant Tgm1(R142C/R142C) mice. RESULTS In the skin of Tgm1(R142C/R142C) mice, expression of the mutant transcripts was comparable with wild-type or Tgm1(+/R142C) mice. However, the amount of mutated protein in the skin was markedly decreased in Tgm1(R142C/R142C) mice, and the TG1 activity of Tgm1(R142C/R142C) keratinocytes was almost lost. Tgm1(R142C/R142C) mice exhibited morphological and functional skin barrier defects and neonatal lethality. The stratum corneum of those mice lacked cornified envelopes, and loricrin, the major structural component, failed to assemble at the corneocyte cell periphery. Tgm1(R142C/R142C) mice showed a marked increase in transepidermal water loss and their skin was easily permeable to toluidine blue dye. The intercellular lipid lamellar structures of the stratum corneum were irregular and the 13-nm periodic X-ray diffractions from the stratum corneum lipid molecules were lost in vivo. CONCLUSION From these results, we suggest that the R142C mutation of TG1 reduces the enzyme stability which is indispensable for development of the stratum corneum and skin barrier function and for postnatal survival of mice.

Varicella-zoster virus-specific cell-mediated immunity in subjects with herpes zoster

Though cell-mediated immunity (CMI) against varicella-zoster virus (VZV) is critical for prevention of the onset of herpes zoster (HZ), clinicians currently lack a simplified procedure to monitor CMI. We have recently developed an assay, called the IFN-γ release assay, and showed that it is a simple and reliable method to determine VZV-specific CMI. In the present study, we applied an IR assay to measure the VZV-specific CMI of patients with HZ. VZV-specific CMI levels were significantly high at the onset of the disease, but were decreased several weeks later. In contrast, CMI VZV-specific antibody titers increased in convalescent phase compared to those in acute phase. Thus, this technology is likely to be very useful in monitoring ongoing VZV-specific immune status.

Bathing suit ichthyosis with summer exacerbation: a temperature-sensitive case.

MADAM, A 27-year-old man complaining of generalized scales came to our clinic. He was born as a collodion baby and had developed ichthyosis after birth. No members of his family or pedigree had the same symptoms. He had no past history of serious diseases other than ichthyosis. On examination, his neck, chest and both sides of his trunk and vertebral regions were covered with slightly brownish, lamellar scales (Fig. 1a,e,g). More severe scales with erythema were on his postauricular and occipital regions, axillary regions, upper back, buttocks, lower abdomen and crural regions covered by his undershorts, and cubital and popliteal regions (Fig. 1b,c,e,i). The distribution of his areas of severe ichthyosis was almost compatible with thermographic images of areas with warmer body temperatures (Fig. 1g–j). Other regions of his face, trunk and extremities revealed only mild scaling. His palms and soles had thin lamellar scales and his fingernails and toenails were thickened (Fig. 1d). Teeth abnormalities, eclabium and ectropion were absent. The patient complained of seasonal changes in his ichthyosis. Indeed, his ichthyosis markedly worsened between 6 May 2010 (Fig. 1e) and 5 August 2010 (Fig. 1f). That summer, an extreme heat wave, over 37 C, occurred during July and August in Japan and the average monthly outside air temperature in the patient’s district increased by more than 10 C between his visits. Haematoxylin and eosin staining of biopsies from his left lumbar lesions showed that the cornified layers were thickened, and epidermal acanthosis and dermal perivascular inflammatory infiltrates were found in severe lesions with erythema and thick scales (Fig. 2a, lower left). In contrast, those characteristics were not evident in mild lesions with only slight scales (Fig. 2a, upper left). Ultrastructure of the lesions revealed that the stratum corneum had piled up to form 36–40 layers in the severe lesions, but was only 10–12 layers thick in the mild lesions. The cornified envelope (marginal band) was hypoplastic in both mild and severe lesions (Fig. 2a, right) and the degradation of corneodesmosomes was delayed in severe lesions (data not shown). The characteristics of the severe lesions represented the skin symptoms of lamellar ichthyosis (LI) and therefore, following approval of the Ethical Committee of the Hyogo College of Medicine and with informed consent of the patient, possible TGM1 mutations were characterized. Mutation analysis of cDNA derived from his hair bulbs revealed compound heterozygous mutations of TGM1, c.430G>A and c.919C>T, which result in p.G144R and p.R307W of transglutaminase 1 (TG1), respectively (Fig. 2b). The same mutations were identified in (a) (b)

Lamellar ichthyosis with pseudoexon activation in the transglutaminase 1 gene

We report a case of a 12‐year‐old boy who was born as a collodion baby after which thick scales developed on his entire body surface. His younger brother showed a similar skin condition. Arcuate‐shaped, large, brownish scales covered his face with ectropion. His lower legs were also covered with larger thick, brownish, plate‐like scales, but other areas were covered with smaller scales. Next‐generation sequencing for exons and splice sites detected a stop‐gain TGM1 mutation leading to p.R71* in transglutaminase 1 (TG1). Another mutation identified was a cryptic mutation in intron 3 that activated a pseudoexon, which was detected by RNA‐based analysis of hair bulbs. The deep intronic mutation caused another truncation mutation, p.N171Tfs*45, in TG1. An in situ TG1 assay demonstrated that TG1 activity was totally lost in this case. Thus, we conclude that the severe phenotype of the patient developed due to those novel compound heterozygous null truncation mutations in TGM1.

Upregulation of interleukin‐33 in the epidermis of two Japanese patients with Netherton syndrome

Netherton syndrome (NS) is a rare autosomal recessive disorder which is caused by mutations in the SPINK5 gene encoding the serine‐protease inhibitor LEKTI. Characteristic symptoms of NS include erythroderma with diffuse desquamation, hair abnormalities and atopic manifestations. Here, we report two Japanese patients with NS, one of whom had a novel mutation in the SPINK5 gene which leads to p.C367Lfs*3. The upregulation of interleukin‐33 (IL‐33) was evident in basal and thickened lower spinous layers of the epidermis in those cases. This suggests that IL‐33 may be involved in the pathophysiology of NS as well as in atopic dermatitis.