Tomonori Oka

CX3CR1 deficiency attenuates imiquimod-induced psoriasis-like skin inflammation with decreased M1 macrophages

BACKGROUND CX3C chemokine receptor 1 (CX3CR1), a receptor for CX3CL1, mediates migration of inflammatory cells. Psoriasis is a common skin disorder that causes skin inflammation. The role of CX3CL1 and CX3CR1 in psoriasis remains unclear. OBJECTIVE To elucidate the role of CX3CL1 and CX3CR1 in psoriasis, we assessed imiquimod-induced psoriasis-like dermatitis in CX3CR1-deficient mice. METHODS We evaluated skin inflammation by assessing erythema, scaling, and ear thickness in CX3CR1(-/-) mice and wild-type (WT) mice. Furthermore, we measured cytokine production by quantitative reverse transcription-PCR. We investigated infiltrating cells in skin by immunohistochemistry and flow cytometry. After confirming phenotypical differences in macrophages between WT and CX3CR1(-/-) mice, we analyzed expression levels of IL-1β, IL-6, and TNF-α in peritoneal macrophages with or without stimulation of CX3CL1. We finally transferred peritoneal macrophages into the ear before IMQ application. RESULTS Skin inflammation assessed by erythema, scaling, and epidermal thickness was significantly reduced in CX3CR1(-/-) mice compared with wild-type (WT) mice, accompanied by decreases in cytokine production for IL-12, IL-23, IL-17A, IL-22, IL-1β, IL-6, TNF-α, and IL-36. On day 6, increase in ear thickness from the baseline of CX3CR1(-/-) mice was one third of that of WT mice. Skin macrophages of CX3CR1(-/-) mice contained increased levels of CCR2 and decreased levels of MCP-1 compared with those from WT mice. Spontaneous expression levels of IL-1β, IL-6, and TNF-α in peritoneal macrophages of naïve CX3CR1(-/-) mice were significantly lower than those of WT mice. Furthermore, stimulation of WT macrophages with CX3CL1 decreased expression of these cytokines, suggesting that altered macrophage populations, but not loss of interaction between CX3CL1 and CX3CR1 signaling, caused differences in cytokine expression and skin inflammation. Moreover, transfer of macrophages from WT mice normalized IMQ-induced psoriasis-like inflammation in CX3CR1(-/-) mice, suggesting that macrophages contributed to the decreased inflammation resulted from CX3CR1 deficiency. CONCLUSION These data show that interactions between CX3CL1 and CX3CR1 play important roles for infiltration of M1 macrophages in a non-inflammatory setting. Decreased M1 macrophages in naïve CX3CR1(-/-) mice may be related to decreased cytokine expression and attenuated psoriasis-like inflammation.

Thymic stromal chemokine TSLP acts through Th2 cytokine production to induce cutaneous T cell lymphoma.

Thymic stromal lymphopoietin (TSLP) activates dendritic cells to induce Th2-mediated inflammation. Periostin, an extracellular matrix protein produced by fibroblasts, induces chronic inflammation by stimulating TSLP production. Recently, a reinforcing cycle linking Th2-type immune responses with periostin-induced keratinocyte activation has been proposed in atopic dermatitis pathogenesis. In this study, we investigated the role of TSLP and periostin in the development of cutaneous T-cell lymphoma (CTCL), where Th2 cytokines and chemokines are also dominant. TSLP and periostin mRNA expression levels were elevated in CTCL lesional skin, both of which correlated with IL4 expression levels. In vitro and ex vivo, IL4 or IL13 stimulated periostin expression by dermal fibroblasts, and fibroblasts from CTCL lesional skin expressed higher levels of periostin than those from control skin. Serum periostin levels of CTCL patients were also significantly higher than those of healthy individuals. Hut78 and MJ, CTCL cell lines, and peripheral blood mononuclear cells from leukemic CTCL patients expressed the TSLP receptor. TSLP induced production of IL4 and IL13 by Hut78 and MJ cells through the activation of STAT5. Moreover, TSLP induced proliferation of CTCL cells both in vitro and in vivo These data suggest that periostin-mediated TSLP production by keratinocytes directly stimulates CTCL tumor cell growth in addition to inducing a Th2-dominant tumor environment in CTCL. Cancer Res; 76(21); 6241-52. ©2016 AACR.

CXCL17 Attenuates Imiquimod-Induced Psoriasis-like Skin Inflammation by Recruiting Myeloid-Derived Suppressor Cells and Regulatory T Cells

CXCL17 is expressed in a variety of cancers and promotes tumor progression by recruiting myeloid-derived suppressor cells (MDSCs). MDSCs suppress tumor immunity by attracting regulatory T cells (Tregs) into tumor sites through CCL5. In this study, we examined the role of CXCL17 in skin disorders. CXCL17 mRNA levels in psoriasis skin, but not in lesional skin of atopic dermatitis or cutaneous T cell lymphoma, were significantly higher than those in normal skin. CXCL17 was mainly expressed in the epidermis, and IFN-γ dose-dependently increased CXCL17 expression by human keratinocytes in vitro. As CXCL17 mRNA expression was increased by treatment with imiquimod (IMQ), we examined the effects of CXCL17 in IMQ-induced psoriasis-like skin inflammation. Injection of recombinant CXCL17 into the ear before and during IMQ application decreased ear thickness, inflammatory cytokine expression, and the number of infiltrating cells compared with PBS injection. Flow cytometric analysis and immunofluorescent staining revealed that the numbers of MDSCs, which are CD11b+Gr-1+, and that of Tregs, which are CD4+CD25+, were higher in the ear of the CXCL17-injected mice than in PBS-injected mice. MDSCs, but not Tregs, showed chemotaxis to CXCL17 in vitro. When mice were injected with anti-CCL5 Ab or anti-CCL4 Ab simultaneously with recombinant CXCL17, ear thickness and cytokine expression increased to a similar level of mice treated with PBS and control IgG, suggesting that these chemokines were important for anti-inflammatory effects. Taken together, CXCL17 attenuates IMQ-induced psoriasis-like skin inflammation by recruiting MDSCs and Tregs, which may be important for regulating excessive inflammation in psoriasis skin.

Elevated serum galectin‐9 levels in patients with atopic dermatitis

Galectin‐9 is a member of the galectin family that has a wide spectrum of biological functions. Among them, galectin‐9 has been known mainly as a potent chemoattractant for eosinophils. In addition, galectin‐9 alters the T‐cell balance by negatively regulating T‐helper (Th)1 and Th17 cells, resulting in Th2 polarization. Atopic dermatitis (AD) is a skin allergic disease characterized by peripheral eosinophilia, mast cell activation and predominance of Th2 cells. To investigate possible roles of galectin‐9 in AD, we measured serum galectin‐9 levels in AD patients and investigated galectin‐9 expression in lesional skin by immunohistochemistry. Serum galectin‐9 levels in patients with AD were significantly higher than those in healthy controls and correlated with the Eczema Area and Severity Index. Serum galectin‐9 levels were decreased after treatment, accompanied by improvement of skin lesions. Immunohistochemical study revealed that galectin‐9 was expressed on epidermal keratinocytes and mast cells in lesional skin of AD. Our results suggest that elevated galectin‐9 expression is associated with progression of AD and that galectin‐9 could be a therapeutic target in AD.

Hematopoietic stem cell transplantation for cutaneous T-cell lymphoma: Summary of 11 cases from two facilities in Japan and Brazil

Some patients with cutaneous T‐cell lymphoma (CTCL) show a miserable clinical course and the only option that can induce long‐term remission for advanced CTCL may be hematopoietic stem cell transplantation (HSCT). So far, studies on HSCT for CTCL patients have been limited. In this study, we summarized 11 cases with CTCL treated with HSCT, including nine cases in Japan and two cases in Brazil. The patients were five cases with mycosis fungoides (MF), two cases with Sézary syndrome (SS), three cases with anaplastic large cell lymphoma, and one case with primary cutaneous peripheral T‐cell lymphoma, not otherwise specified (PTL‐NOS). Currently, seven out of 11 cases are alive (at 13–108 months after transplantation) and four died at 15 days to 14 months after transplantation. When focusing on the eight patients who received allogeneic HSCT for MF/SS and PTL‐NOS, all four patients at 45 years old or under are alive at present. One case showed relapse in the skin. On the other hand, one out of the other four patients at over 45 years old survived. Engraftment failure was seen in one case and all the other three cases experienced relapse. Although this is only a case series with a small number, our study has suggested that we should be careful about age when treating patients with MF/SS by allogeneic HSCT.

Scleroderma en coup de sabre with recurrent episodes of brain hemorrhage

We report a 39‐year‐old man referred to our facility with linear sclerotic lesions along the several Blaschkos lines of the scalp. A year before the referral, he had had an episode of brain hemorrhage, although there was no evidence of vascular malformation or any other risk factors of brain hemorrhage for his young age. On the diagnosis of scleroderma en coup de sabre, prednisolone intake was initiated, and the skin lesions were well controlled. However, in the course of our follow up, he had another episode of brain hemorrhage, again without any evidence of cerebral vascular abnormalities. Organic intracranial abnormalities in this disease are well‐documented, but there have been few reports on comorbid recurrent brain hemorrhages. We herein discuss the possible relationship of the skin lesions with the brain hemorrhages in our case, taking notice of the implication of developmental abnormalities behind these apparently independent phenomena inside and outside the cranium.

Placental Growth Factor and Vascular Endothelial Growth Factor Together Regulate Tumour Progression via Increased Vasculature in Cutaneous T-cell Lymphoma

Angiogenesis is regarded as an essential step in supporting tumour growth and metastasis. In haematological malignancies, including cutaneous T-cell lymphoma (CTCL), angiogenesis is increased and serum levels of some pro-angiogenic markers are elevated. The aim of this study was to investigate expression levels of placental growth factor (PlGF) and vascular endothelial growth factor (VEGF)-A in lesional skin and sera in patients with CTCL, and to assess the association of these factors with development of CTCL. A further aim was to investigate the effect of PlGF on lymphoma cell growth in vivo using a tumour inoculation model. Expression of PlGF and VEGF-A were significantly elevated in CTCL skin. Tumour cells expressed PlGF in some cases. Serum PlGF levels were increased in patients with advanced CTCL and correlated with disease markers. Moreover, PlGF enhanced lymphoma cell growth in vivo through increasing tumour vasculature. These findings suggest that angiogenesis plays a role in the progression of CTCL and raises the possibility of using inhibitors of PlGF in CTCL therapy.

Increased syndecan-4 expression in sera and skin of patients with atopic dermatitis

Syndecan-4 (SDC-4) is a cell surface proteoglycan, which participates in signaling during cell adhesion, migration, proliferation, endocytosis, and mechanotransduction, and is expressed on various cells, including endothelial cells, epithelial cells, T cells, and eosinophils. Emerging evidences have suggested that SDC-4 might contribute to Th2-driven allergic immune responses. Here, we examined the role of SDC-4 in patients with atopic dermatitis (AD). Serum SDC-4 levels in AD patients were significantly higher than in healthy individuals, and they increased according to the disease severity. Importantly, they positively correlated with Eczema Area and Severity Index and itch visual analogue scale scores. Furthermore, serum SDC-4 levels decreased after treatment. We also analyzed SDC-4 expression in AD lesional skin. SDC-4 mRNA levels in AD skin were significantly higher than those of normal skin. Immunohistochemical staining revealed that SDC-4 was highly expressed in the epidermis and endothelial cells in AD lesional skin. Taken together, our study has demonstrated that SDC-4 expression was increased in sera and skin of AD patients, suggesting that SDC-4 may contribute to the development of AD.

Serum vascular endothelial growth factor A levels reflect itch severity in mycosis fungoides and Sézary syndrome

Angiogenesis is an important step to support progression of malignancies, including mycosis fungoides (MF) and Sézary syndrome (SS). Vascular endothelial growth factor (VEGF)‐A, a key player in angiogenesis, is secreted by tumor cells of MF/SS and its expression levels in lesional skin correlated with disease severity. In this study, we examined serum VEGF‐A levels in MF/SS patients. Serum VEGF‐A levels were elevated in patients with erythrodermic MF/SS and the levels decreased after treatment. Importantly, serum VEGF‐A levels positively correlated with markers for pruritus. We also found that VEGF‐A upregulated mRNA expression of thymic stromal lymphopoietin by keratinocytes. Taken together, our study suggests that VEGF‐A can promote progression and pruritus in MF/SS. Inhibition of VEGF‐A signaling can be a therapeutic strategy for patients with erythrodermic MF/SS.

Increased Interleukin-19 Expression in Cutaneous T-cell Lymphoma and Atopic Dermatitis

Interleukin-19 (IL-19), a pro-inflammatory cytokine known to stimulate the production of T helper type 2 (Th2) cytokines, is induced by IL-17A and highly expressed in the lesional skin of psoriasis and atopic dermatitis (AD). This aim of this study was to investigate whether IL-19 is involved in cutaneous T-cell lym-phoma (CTCL) and AD. IL-19 levels were significantly higher in the sera of patients with AD and those with advanced-stage CTCL than in normal controls, correlating significantly with clinical disease markers. IL-19 mRNA levels in lesional skin of both diseases were significantly elevated. Immunohistochemical staining revealed that IL-19 was expressed in the epidermis of AD skin and CTCL skin. In vitro, IL-17A and IL-4 increased IL-19 mRNA expression in human keratinocytes. Thus, IL-19 was increased in the sera and skin of AD and CTCL. These results suggest that IL-19 is important for bridging Th17 to Th2 in these diseases.