A phenotypic analysis of involucrin-mOVA mice following adoptive transfer of OVA-specific CD8+ T cells

To investigate the mechanism of autoimmunity and peripheral tolerance in the skin, several transgenic mouse strains expressing membrane-bound ovalbumin (mOVA) as an epidermal self-antigen under the control of keratinocyte-specific promotors, such as keratin 5 and keratin 14, were employed in combination with adoptive transfer of CD8⁺ T cells from OT-I mice (OT-I T cells) that recognize an ovalbumin-derived peptide. However, these strains showed bodyweight loss and required additional inflammatory stimuli, such as γ-irradiation and tape-stripping, to induce skin inflammation. In this study, we generated a mouse strain expressing mOVA under the control of human involucrin promoter (involucrin-mOVA mice). In contrast to previous strains, involucrin-mOVA mice spontaneously developed skin inflammation after the transfer of OT-I T cells in the absence of external stimuli without significant bodyweight loss. We focused on the skin infiltration process of OT-I T cells and found that transferred OT-I T cells accumulated around the hair follicles in the early phase of skin inflammation, and in the later phase, the skin inflammation spontaneously resolved despite the remaining OT-I T cells in the skin. Our involucrin-mOVA mice will provide a promising tool to investigate the pathogenesis and the tolerance mechanisms of cytotoxic skin autoimmunity.

Density dependence of retention factors of trans-stilbene oxide for chiral separation by supercritical fluid chromatography

Retention factors for two enantiomers of trans-stilbene oxide, k₁ and k₂, were measured with a chiral AD-H column using two syringe pumps to feed CO₂ and methanol as a co-solvent at various temperatures, pressures and co-solvent mole fractions to determine the effects of these operating conditions on the retention factors. The retention factors k₁ and k₂ are for the (R,R)- and (S,S)-forms, respectively. When the isothermal compressibilities of a mixture of CO₂ and MeOH were lower than 0.01, far from the critical locus of the CO₂ and methanol mixture, both retention factors were well expressed with the solvent density and temperature with an average absolute relative deviation of 1-2%. In the vicinity of the critical locus, however, where the isothermal compressibilities were much larger than 0.01, the relationship between retention factor and density was complicated. Both retention factors were proportional to the isothermal compressibility, irrespective of methanol mole fraction at each temperature.

Platelets Regulate the Migration of Keratinocytes via Podoplanin/CLEC-2 Signaling during Cutaneous Wound Healing in Mice

Podoplanin is an endogenous ligand for C-type lectin-like receptor 2 (CLEC-2), which is expressed on platelets. Recent evidence indicates that this specific marker of lymphatic endothelial cells is also expressed by keratinocytes at the edge of wounds. However, whether podoplanin or platelets play a role in keratinocyte activity during wound healing remains unknown. We evaluated the effect of podoplanin expression levels on keratinocyte motility using cultured primary normal human epidermal keratinocytes (NHEKs). Down-regulation of podoplanin in NHEKs via transfection with podoplanin siRNA inhibited their migration, indicating that podoplanin plays a mandatory role in this process. In addition, down-regulation of podoplanin was correlated with up-regulation of E-cadherin, suggesting that podoplanin-mediated stimulation of keratinocyte migration is associated with a loss of E-cadherin. Both the addition of platelets and treatment with CLEC-2 inhibited the migration of NHEKs. The down-regulation of RhoA activity and the up-regulation of E-cadherin in keratinocytes were also induced by CLEC-2. In conclusion, these results suggest that podoplanin/CLEC-2 signaling regulates keratinocyte migration via modulating E-cadherin expression through RhoA signaling. Altering the regulation of keratinocyte migration by podoplanin might be a novel therapeutic approach to improve wound healing.

Calcipotriol increases hCAP18 mRNA expression but inhibits extracellular LL37 peptide production in IL-17/IL-22-stimulated normal human epidermal keratinocytes

Interleukins (IL)-17A and -22 are involved in the patho-genesis of psoriasis. Cathelicidin LL37 serves as not only antimicrobial peptide but also as autoinflammatory mediator. 1,25-Dihydroxyvitamin D3 analogues, such as calcipotriol, are used as topical treatment for psoriasis. However, the effect of calcipotriol on the mRNA expression/production of human cathelicidin antimicrobial protein (hCAP18) and LL37 peptide by IL-17A/IL-22-stimulated keratinocytes remains controversial. To evaluate the modulatory action of calcipotriol on the production of hCAP18 and LL37, we analysed hCAP18 mRNA expression and hCAP18/LL37 peptide production in IL-17A/IL-22-stimulated cultured human keratinocytes by real-time qPCR, ELISA, western blotting, and immunocytostaining. By western blotting, hCAP18 protein was detected in keratinocytes cultured for 72 h with IL-17/IL-22. Calcipotriol increased hCAP18 mRNA expression in IL-17/IL-22-stimulated keratinocytes. However, LL37 peptide in the culture supernatants was reduced by calcipotriol. Immunostaining revealed that the overproduced LL37 resides within the cells. LL37 promotes psoriasis via interaction with extracellular DNA, but may suppress psoriasis by interfering cytosolic DNA.

Lymphangiogenesis and angiogenesis in abdominal aortic aneurysm

The pathogenesis of abdominal aortic aneurysm (AAA) is characterized to be inflammation-associated degeneration of vascular wall. Neovascularization is regularly found in human AAA and considered to play critical roles in the development and rupture of AAA. However, little is known about lymphangiogenesis in AAA. The purpose of this study was to demonstrate both angiogenesis and lymphangiogenesis in AAA. Abdominal aortic tissue was harvested either from autopsy (control group) and during open-repair surgery for AAA (AAA group). Adventitial lymphatic vasa vasorum was observed in both groups, but seemed to be no significant morphological changes in AAA. Immunohistochemical studies identified infiltration of lymphatic vessel endothelial hyaluronan receptor (LYVE) -1, vascular endothelial growth factor (VEGF)-C, and matrix metalloproteinase (MMP)-9-positive macrophages and podoplanin and Prox-1-positive microvessels in the intima/media in AAA wall, where hypoxia-inducible factors (HIF)-1α was expressed. VEGF-C and MMP-9 were not expressed in macrophages infiltrating in the adventitia. Intraoperative indocyanine green fluorescence lymphography revealed lymph stasis in intima/medial in AAA. Fluorescence microscopy of the collected samples also confirmed the accumulation of lymph in the intima/media but not in adventitia. These results demonstrate that infiltration of macrophages in intima/media is associated with lymphangiogenesis and angiogenesis in AAA. Lymph-drainage appeared to be insufficient in the AAA wall.

Potential application of in vivo imaging of impaired lymphatic duct to evaluate the severity of pressure ulcer in mouse model

Ischemia-reperfusion (IR) injury is a cause of pressure ulcer. However, a mechanism underlying the IR injury-induced lymphatic vessel damage remains unclear. We investigated the alterations of structure and function of lymphatic ducts in a mouse cutaneous IR model. And we suggested a new method for evaluating the severity of pressure ulcer. Immunohistochemistry showed that lymphatic ducts were totally vanished by IR injury, while blood vessels were relatively preserved. The production of harmful reactive oxygen species (ROS) was increased in injured tissue. In vitro study showed a high vulnerability of lymphatic endothelial cells to ROS. Then we evaluated the impaired lymphatic drainage using an in vivo imaging system for intradermally injected indocyanine green (ICG). The dysfunction of ICG drainage positively correlated with the severity of subsequent cutaneous changes. Quantification of the lymphatic duct dysfunction by this imaging system could be a useful strategy to estimate the severity of pressure ulcer.

VEGF-A promotes IL-17A-producing γδ T cell accumulation in mouse skin and serves as a chemotactic factor for plasmacytoid dendritic cells

BACKGROUND

IL-17-producing CD4(+) T (Th17) cells and their cytokines, IL-17A and IL-22, are deeply involved in the pathogenesis of psoriasis by stimulating epidermal keratinocytes to proliferate and to produce cytokines/chemokines and vascular endothelial growth factor (VEGF)-A. Plasmacytoid dendritic cells (pDCs), infiltrating in psoriatic lesions, are known to exacerbate the Th17-mediated pathogenesis of psoriasis.

OBJECTIVE

To address the initiative role of VEGF-A in the development of psoriasis and the pDC accumulation.

METHODS

Numerical changes and VEGF receptor 1 (VEGFR1) and VEGFR2 expressions were investigated in skin-infiltrating T cells and pDCs of K14-VEGF-A transgenic (Tg) and wild type (WT) mice. The chemotactic properties of VEGF-A for purified splenic pDCs were also evaluated by real-time chemotaxis assay.

RESULTS

By flow cytometry and immunohistochemistry, we observed that the number of dermal IL-17A(+) γδ T cells, but not CD4(+) T cells, was increased in VEGF-A Tg mice, suggesting that the main source of IL-17A was γδ T cells. Moreover, we identified pDCs as 440c(+) cells by immunohistochemistry and as PDCA-1(+)B220(+) cells by flow cytometry, and found that pDCs infiltrated at a higher frequency in VEGF-A Tg than WT mice. pDCs, but not γδ T cells, isolated from the skin expressed VEGFR1 and VEGFR2. Freshly isolated splenic pDCs expressed both receptors after 48-h cultivation. pDCs did not produce cytokines in response to VEGF-A, however, they had a strong velocity of chemotaxis toward VEGF-A at a comparable level to chemerin.

CONCLUSIONS

These findings suggest that VEGF-A functions as not only a downstream enhancer but also an upstream initiator by chemoattracting pDCs in psoriatic lesions.

Mutations in SERPINB7, encoding a member of the serine protease inhibitor superfamily, cause Nagashima-type palmoplantar keratosis

"Nagashima-type" palmoplantar keratosis (NPPK) is an autosomal recessive nonsyndromic diffuse palmoplantar keratosis characterized by well-demarcated diffuse hyperkeratosis with redness, expanding on to the dorsal surfaces of the palms and feet and the Achilles tendon area. Hyperkeratosis in NPPK is mild and nonprogressive, differentiating NPPK clinically from Mal de Meleda. We performed whole-exome and/or Sanger sequencing analyses of 13 unrelated NPPK individuals and identified biallelic putative loss-of-function mutations in SERPINB7, which encodes a cytoplasmic member of the serine protease inhibitor superfamily. We identified a major causative mutation of c.796C>T (p.Arg266(∗)) as a founder mutation in Japanese and Chinese populations. SERPINB7 was specifically present in the cytoplasm of the stratum granulosum and the stratum corneum (SC) of the epidermis. All of the identified mutants are predicted to cause premature termination upstream of the reactive site, which inhibits the proteases, suggesting a complete loss of the protease inhibitory activity of SERPINB7 in NPPK skin. On exposure of NPPK lesional skin to water, we observed a whitish spongy change in the SC, suggesting enhanced water permeation into the SC due to overactivation of proteases and a resultant loss of integrity of the SC structure. These findings provide an important framework for developing pathogenesis-based therapies for NPPK.

High frequencies of positive nickel/cobalt patch tests and high sweat nickel concentration in patients with intrinsic atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is classified into extrinsic AD with high serum IgE levels and impaired barrier, and intrinsic AD with low serum IgE levels and unimpaired barrier. Intrinsic AD has a lower frequency of FLG mutations and a higher frequency of circulating Th1 cells, implying that non-protein antigens, represented by metals, may be an exacerbation factor in intrinsic AD.

OBJECTIVE

To investigate metal allergy in intrinsic AD.

METHODS

Enrolled in this study were 86 Japanese AD patients seen in three university hospitals, consisting of 55 extrinsic and 31 intrinsic AD patients. Patch testing was performed, focusing on nickel, cobalt, and chrome, in parallel with other 14 metals. FLG mutations were analyzed in 49 patients (extrinsic, 29; intrinsic, 20). In 17 patients (extrinsic, 12; intrinsic, 5), sweat was collected from the forearms by exercise, and the concentration of nickel was fluorometrically measured.

RESULTS

Nickel, cobalt, and chrome were the major positive metals. Intrinsic AD showed significantly higher percentages of positive reactions than extrinsic AD to nickel (intrinsic 41.9% vs extrinsic 16.4%, P=0.019) and cobalt (38.7% vs 10.9%, P=0.005). There was no significant difference between FLG mutation-bearing and non-bearing patients. The concentration of nickel was higher in the sweat of intrinsic AD than extrinsic AD patients (333.8 vs 89.4ng/g, P=0.0005) and inversely correlated with serum IgE levels.

CONCLUSIONS

Nickel and cobalt allergy may be involved in intrinsic AD. Given that the metals are excreted through sweat, intrinsic AD might be exaggerated by highly metal-containing sweat.

Kallikrein-related peptidase 5 functions in proteolytic processing of profilaggrin in cultured human keratinocytes

Filaggrin protein is synthesized in the stratum granulosum of the skin and contributes to the formation of the human skin barrier. Profilaggrin is cleaved by proteolytic enzymes and converted to functional filaggrin, but its processing mechanism remains not fully elucidated. Kallikrein-related peptidase 5 (KLK5) is a major serine protease found in the skin, which is secreted from lamellar granules following its expression in the stratum granulosum and activated in the extracellular space of the stratum corneum. Here, we searched for profilaggrin-processing protease(s) by partial purification of epidermal extracts and found KLK5 as a possible candidate. We used high performance liquid chromatography coupled with electrospray tandem mass spectrometry to show that KLK5 cleaves profilaggrin. Furthermore, based on a proximity ligation assay, immunohistochemistry, and immunoelectron microscopy analysis, we reveal that KLK5 and profilaggrin co-localize in the stratum granulosum in human epidermis. KLK5 knockdown in normal cultured human epidermal keratinocytes resulted in higher levels of profilaggrin, indicating that KLK5 potentially functions in profilaggrin cleavage.

D1-like dopamine receptors antagonist inhibits cutaneous immune reactions mediated by Th2 and mast cells

BACKGROUND

Dopamine transduces signals via five subtypes of G protein-coupled receptors. Among these subtypes, the D1 and D5 receptors belong to the D1-like group. Although dopamine is known to mediate immune responses, its involvement in cutaneous immunity remains unclear.

OBJECTIVE

The aim of this study is to determine the role of dopamine and its D1-like receptors in cutaneous immune responses.

METHODS

By using the D1-like receptor antagonist SCH 23390, we examined the role of D1-like receptors in murine models of Th1-type contact hypersensitivity and Th2-type atopic dermatitis in vivo, and in mast cells and Th2 cell differentiation in vitro.

RESULTS

Administration of SCH 23390 did not affect Th1-type contact hypersensitivity but suppressed the immediate-type reaction (ITR) and the late phase reaction (LPR) in the atopic dermatitis model. In addition, SCH 23390-treated mice showed higher IFN-γ and lower IL-4 mRNA levels in the ear skin of challenged mice than did non-treated mice as analyzed by real-time RT PCR. Consistently, the passive cutaneous anaphylaxis reaction was significantly reduced in SCH 23390-treated mice. Moreover, dopamine enhanced mast cell degranulation and Th2 cell differentiation, and both activities were abrogated by SCH 23390.

CONCLUSION

These findings suggest that the D1-like receptors mediate immediate and late phase skin reactions by promoting Th2 induction and mast cell degranulation.

Identification of mutations in the prostaglandin transporter gene SLCO2A1 and its phenotype-genotype correlation in Japanese patients with pachydermoperiostosis

BACKGROUND

Pachydermoperiostosis (PDP) is a rare genetic disorder characterized by 3 major symptoms: pachydermia including cutis verticis gyrata (CVG), periostosis, and finger clubbing. Recently, a homozygous mutation in the gene HPGD, which encodes 15-hydroxyprostaglandin dehydrogenase (15-PGDH), was found to be associated with PDP. However, mutations in HPGD have not been identified in Japanese PDP patients.

OBJECTIVE

We aimed to identify a novel responsible gene for PDP using whole exome sequencing by next-generation DNA sequencer (NGS).

METHODS

Five patients, including 2 patient-parent trios were enrolled in this study. Entire coding regions were sequenced by NGS to identify candidate mutations associated with PDP. The candidate mutations were subsequently sequenced using the Sanger method. To determine clinical characteristics, we analyzed histological samples, as well as serum and urinary prostaglandin E2 (PGE2) levels for each of the 5 PDP patients, and 1 additional patient with idiopathic CVG.

RESULTS

From initial analyses of whole exome sequencing data, we identified mutations in the solute carrier organic anion transporter family, member 2A1 (SLCO2A1) gene, encoding prostaglandin transporter, in 3 of the PDP patients. Follow-up Sanger sequencing showed 5 different SLCO2A1 mutations (c.940+1G>A, p.E427_P430del, p.G104*, p.T347I, p.Q556H) in 4 unrelated PDP patients. In addition, the splice-site mutation c.940+1G>A identified in 3 of 4 PDP patients was determined to be a founder mutation in the Japanese population. Furthermore, it is likely that the combination of these SLCO2A1 mutations in PDP patients is also associated with disease severity.

CONCLUSION

We found that SLCO2A1 is a novel gene responsible for PDP. Although the SLCO2A1 gene is only the second gene discovered to be associated with PDP, it is likely to be a major cause of PDP in the Japanese population.

A group of atopic dermatitis without IgE elevation or barrier impairment shows a high Th1 frequency: possible immunological state of the intrinsic type

BACKGROUND

Atopic dermatitis (AD) can be classified into the major extrinsic type with high serum IgE levels and impaired barrier, and the minor intrinsic type with normal IgE levels and unimpaired barrier.

OBJECTIVE

To characterize the intrinsic type of Japanese AD patients in the T helper cell polarization in relation to the barrier condition.

METHODS

Enrolled in this study were 21 AD patients with IgE<200kU/L (IgE-low group; 82.5±59.6kU/L) having unimpaired barrier, and 48 AD patients with IgE>500kU/L (IgE-high group; 8.050±10.400kU/L). We investigated filaggrin gene (FLG) mutations evaluated in the eight loci common to Japanese patients, circulating Th1, Th2 and Th17 cells by intracellular cytokine staining and flow cytometry, and blood levels of CCL17/TARC, IL-18, and substance P by ELISA.

RESULTS

The incidence of FLG mutations was significantly lower in the IgE-low group (10.5%) than the IgE-high group (44.4%) (normal individuals, 3.7%). The percentage of IFN-γ-producing Th1, but not Th2 or Th17, was significantly higher in the IgE-low than IgE-high group. Accordingly, Th2-attracting chemokine CCL17/TARC, was significantly lower in the IgE-low than the IgE-high group. There were no differences between them in serum IL-18 levels, or the plasma substance P levels or its correlation with pruritus.

CONCLUSION

The IgE-low group differed from the IgE-high group in that it had much less FLG mutations, increased frequency of Th1 cells, and lower levels of CCL17. In the intrinsic type, non-protein antigens capable of penetrating the unimpaired barrier may induce a Th1 eczematous response.

The mandatory role of IL-10-producing and OX40 ligand-expressing mature Langerhans cells in local UVB-induced immunosuppression

The mechanism underlying the local UVB-induced immunosuppression is a central issue to be clarified in photoimmunology. There have been reported a considerable number of cells and factors that participate in the sensitization phase-dependent suppression, including Langerhans cells (LCs), regulatory T cells, IL-10, and TNF-alpha. The recent important finding that LC-depleted mice rather exhibit enhanced contact hypersensitivity responses urged us to re-evaluate the role of LCs along with dermal dendritic cells (dDCs) in the mechanism of UVB-induced immunosuppression. We studied the surface expression of OX40 ligand (OX40L) and the intracellular expression of IL-10 in LCs and dDCs from UVB-irradiated (300 mJ/cm(2)) skin of BALB/c mice and those migrating to the regional lymph nodes from UVB-irradiated, hapten-painted mice. In epidermal and dermal cell suspensions prepared from the UVB-irradiated skin, LCs expressed OX40L as well as CD86 and produced IL-10 at a higher level than Langerin(-) dDCs. The UVB-induced immunosuppression was attenuated by the administration of IL-10-neutralizing or OX40L-blocking Abs. In mice whose UVB-irradiated, hapten-painted skin was dissected 1 d after hapten application, the contact hypersensitivity response was restored, because this treatment allowed dDCs but not LCs to migrate to the draining lymph nodes. Moreover, LC-depleted mice by using Langerin-diphtheria toxin receptor-knocked-in mice showed impaired UVB-induced immunosuppression. These results suggest that IL-10-producing and OX40L-expressing LCs in the UVB-exposed skin are mandatory for the induction of Ag-specific regulatory T cells.

Flaky tail mouse denotes human atopic dermatitis in the steady state and by topical application with Dermatophagoides pteronyssinus extract

The barrier abnormality, a loss-of-function mutation in the gene encoding filaggrin (FLG), which is linked to the incidence of atopic dermatitis (AD), is a recently discovered but important factor in the pathogenesis of AD. Flaky tail (Flg(ft)) mice, essentially deficient in filaggrin, have been used to investigate the role of filaggrin on AD. However, the relevancy of Flg(ft) mice to human AD needs to be determined further. In this study, we observed the clinical manifestations of Flg(ft) mice in the steady state and their cutaneous immune responses against external stimuli, favoring human AD. Under specific pathogen-free conditions, the majority of Flg(ft) mice developed clinical and histological eczematous skin lesions similar to human AD with outside-to-inside skin barrier dysfunction evaluated by newly devised methods. In addition, cutaneous hapten-induced contact hypersensitivity as a model of acquired immune response and a mite extract-induced dermatitis model physiologically relevant to a human AD were enhanced in Flg(ft) mice. These results suggest that the Flg(ft) mouse genotype has potential as an animal model of AD corresponding with filaggrin mutation in human AD.