Increased IL-26 Expression Promotes T Helper Type 17- and T Helper Type 2-Associated Cytokine Production by Keratinocytes in Atopic Dermatitis.

Whereas atopic dermatitis (AD) is considered as a T helper 2 (Th2)-centered disease, IL-17-producing Th (Th17) cells are also activated in AD lesional skin. However, the relationship between Th17 responses and Th2 responses in AD is still to be elucidated. Although Th17 cells are increased in AD skin, the expression and function of IL-26, which is also produced by Th17 cells, in AD are still unknown. In this report, we demonstrated that IL-26 mRNA expression levels were elevated in AD lesional skin compared with healthy controls and that IL-26-producing cells were increased in AD lesional skin by immunohistochemistry. Furthermore, IL-26 promoted IL-8, IL-1ß, chemokine (C-C motif) ligand 20, IL-33, and ß-defensin 2 production in keratinocytes through phosphorylation of signal transducer and activator of transcription 1 and signal transducer and activator of transcription 3. Selective JAK inhibitors for JAK1, JAK2, and tyrosine kinase 2 blocked IL-26-induced cytokine production in keratinocytes. We also showed that injection of IL-26 exacerbated an oxazolone-induced AD mouse model and upregulated Th2 and Th17 cytokine expression in vivo. Because previous studies indicate that the above molecules induced by IL-26 can promote Th17 and/or Th2 immune responses, IL-26 may play an important role for bridging between Th17 and Th2 responses, resulting in the development of AD.

YKL-40 Promotes Proliferation of Cutaneous T-Cell Lymphoma Tumor Cells through Extracellular Signal-Regulated Kinase Pathways.

YKL-40, one of the chitinase-like proteins, is associated with the pathogenesis of a wide variety of human diseases through modulation of inflammation and tissue remodeling by its diverse roles in cell proliferation, differentiation, and survival. Emerging evidence shows that aberrantly expressed YKL-40 promotes the development of malignancies by inducing proliferation of tumor cells, cytokine production, and angiogenesis by acting on various stromal cells, immune cells, and tumor cells. In this study, we investigated the expression and function of YKL-40 in cutaneous T-cell lymphoma (CTCL). We first revealed that serum YKL-40 levels were increased in patients with CTCL and correlated with disease severity markers. We also found that YKL-40 was expressed by epidermal keratinocytes and tumor cells in lesional skin of CTCL by immunohistochemistry. Although YKL-40 did not affect cytokine production from CTCL cell lines, YKL-40 promoted the proliferation of Hut78 cells and HH cells in vitro, which was dependent on extracellular signal-regulated kinase 1/2 pathways. Moreover, exogenous YKL-40 administration enhanced tumor growth of HH cells in vivo. Our study has suggested that YKL-40 produced from epidermal keratinocytes and CTCL cells promoted the proliferation of CTCL cells through extracellular signal-regulated kinase 1/2 pathways in autocrine and paracrine manners, leading to development of CTCL.

Possible therapeutic applicability of galectin-9 in cutaneous T-cell lymphoma.

BACKGROUND: Galectin-9, a member of the galectin family, can promote tumor growth through inducing apoptosis in anti-tumor immune cells via T cell immunoglobulin and mucin domain 3 (TIM-3). On the other hand, galectin-9 also induces tumor cell apoptosis in many malignancies and thought to have potential as an anti-cancer agent. OBJECTIVE: To examine the expression and therapeutic applicability of galectin-9 in cutaneous T-cell lymphoma (CTCL). METHODS: Galectin-9 expression in lesional skin and sera was measured using CTCL samples. The effect of galectin-9 on CTCL cell lines was investigated in vitro. We also examined effect of galectin-9 on tumor growth of CTCL cells in immune-deficient mice. Moreover, we examined the efficacy of galectin-9, anti-TIM-3 blocking antibody, or their combination on tumor growth of EL-4 cells in wild-type mice. RESULTS: Galectin-9 was expressed on tumor cells in lesional skin of CTCL and the expression levels were associated with decreased CD8+ T-cell infiltration. Serum galectin-9 levels were correlated with disease severity markers. High-dose galectin-9 induced cell death of CTCL cell lines through activation of caspase-3 and caspase-9, independently of TIM-3. High-dose galectin-9 suppressed the growth of CTCL cells and EL-4 cells in vivo. Furthermore, additional anti-TIM-3 blocking antibody administration to galectin-9 achieved greater inhibition of tumor growth compared to single administration. CONCLUSION: Galectin-9 expression on tumor cells may be associated with CTCL progression through attenuating anti-tumor immunity. On the other hand, exogenous high-dose galectin-9 administration can be a therapeutic strategy for CTCL and anti-TIM-3 blocking antibody can augment the efficacy of galectin-9.

Expression of CCR3 and CCR4 Suggests a Poor Prognosis in Mycosis Fungoides and Sézary Syndrome.

Tumor cells in cutaneous T-cell lymphoma express limited numbers of chemokine receptors. We investigated the expression patterns of CXCR3, CCR3, CCR4 and CCR10 in mycosis fungoides, Sézary syndrome, lym-phomatoid papulosis and anaplastic large cell lymphoma in 121 skin biopsy samples. CXCR3 was expressed in 86% of mycosis fungoides cases but in no anaplastic large cell lymphoma cases. CCR3 was expressed in 73% of cases of CD30+ lymphoproliferative disorders such as lymphomatoid papulosis and anaplastic large cell lymphoma. Mycosis fungoides/Sézary syndrome patients with high CCR3 or CCR4 expression had a poorer survival prognosis than mycosis fungoides/Sézary syndrome patients whose tumor cells did not express these receptors. CCR10 was expressed in 50% of mycosis fungoides/Sézary syndrome cases and in 13% of cases with CD30+ lym-phoproliferative disorders. These results suggest that differential patterns of CXCR3, CCR3, CCR4 and CCR10 expression are useful for the diagnosis of cutaneous T-cell lymphoma. Moreover, expression of CCR3 or CCR4 suggests a poor prognosis in mycosis fungoides/Sézary syndrome.

Sézary syndrome without erythroderma: A case report and review of published work.

Sézary syndrome (SS) is defined by erythroderma and circulating atypical T cells, with or without lymphadenopathy. Recently, Thompson et al. identified a distinct population of SS patients with an atypical presentation: a high blood tumor burden of Sézary cells fulfilling criteria for SS but without fulfilling the criteria for erythroderma at the diagnosis. Here, we report a case of a 49-year-old Japanese man with SS who did not present with erythroderma initially, but exhibited erythematous itchy papules symmetrically located on the legs and arms. We also reviewed reported cases of SS without initial erythroderma. The skin manifestations at diagnosis varied from patches to tumors often seen in mycosis fungoides, and other rarer findings such as excoriation, palmoplantar keratoderma and alopecia. Pruritus was reported in most patients (86%), unlike early mycosis fungoides, and could be the main clue to the diagnosis of SS. Notably, three patients were reported to have presented with papular lesions, similar to our case. Little is known about why skin lesions in SS without erythroderma vary and why these cases did not exhibit erythroderma initially. Attenuated stimulation by colonized Staphylococcus aureus, impairment in recruitment of malignant T cells and suppression of inflammatory response induced by malignant T cells with regulatory phenotype may be associated with skin manifestations. Further studies are necessary to elucidate the etiology of this entity.

Decreased progranulin expression in Mycosis fungoides: a possible association with the high frequency of skin infections.

Progranulin (PGRN) is a multi-functional protein known to be involved in diverse biological processes, including tumourigenesis, anti-inflammation, and anti-infection. PGRN expression in sera or tissues is elevated in a variety of malignancies and is associated with poor prognosis. However, it remains to be determined whether PGRN is involved in Mycosis fungoides (MF). To investigate the roles of PGRN in MF. Serum PGRN levels were measured in patients with MF and normal controls by enzyme-linked immunosorbent assay. PGRN expression in MF and normal skin was examined by quantitative reverse transcription polymerase chain reaction and immunohistochemistry. Moreover, we analysed correlations between the expression levels of PGRN and antimicrobial peptides in lesional skin. PGRN levels were significantly lower in sera of MF patients than those of normal controls. PGRN mRNA levels in lesional skin of MF were also significantly decreased. Immunohistochemical staining revealed that PGRN was expressed in epidermal keratinocytes of normal controls, however, PGRN expression in epidermal keratinocytes was also weaker in MF skin. Furthermore, significant inverse correlations were identified between PGRN and antimicrobial peptide mRNA expression. These results suggest that low PGRN expression may contribute to the frequent occurrence of skin infections in patients with MF.

Aberrant CD137 ligand expression induced by GATA6 overexpression promotes tumor progression in cutaneous T-cell lymphoma.

CD137 and its ligand, CD137L, are expressed on activated T cells and antigen-presenting cells, respectively. Recent studies have shown that CD137L and CD137 are aberrantly expressed by tumor cells, especially in some hematopoietic malignancies, and interactions between these molecules on tumor cells promote tumor growth. In this study, we investigated the roles of CD137L and CD137 in cutaneous T-cell lymphoma (CTCL), represented by mycosis fungoides and Sézary syndrome. Flow cytometric analysis showed that primary Sézary cells and CTCL cell lines (Hut78, MyLa, HH, SeAx, and MJ) aberrantly expressed CD137L. CD137L expression by tumor cells in CTCL was also confirmed by immunohistochemistry. Anti-CD137L-neutralizing antibody inhibited proliferation, survival, CXCR4-mediated migration, and in vivo growth in CTCL cell lines through inhibition of phosphorylation of AKT, extracellular signal-regulated kinase 1/2, p38 MAPK, and JNK. Moreover, suppression of CD137L signaling decreased antiapoptotic proteins Bcl-2 and phosphorylated Bad. We also explored the transcription factor regulating CD137L expression. Because GATA6 has been proposed as an oncogene in many types of tumors with aberrant CD137L expression, we examined GATA6 expression and the involvement of GATA6 in CD137L expression in CTCL. DNA hypomethylation and histone acetylation induced GATA6 overexpression in CTCL cells. Furthermore, chromatin immunoprecipitation, luciferase reporter assay, and knockdown by short hairpin RNA showed that GATA6 directly upregulated CD137L expression. Inhibition of GATA6 resulted in decreased survival and in vivo growth in CTCL cells. Collectively, our findings prompt a novel therapeutic approach to CTCL based on the discovery that the GATA6/CD137L axis plays an important role in the tumorigenesis of CTCL.