Cytotoxic CD4+ T cells eliminate senescent cells by targeting cytomegalovirus antigen.

Senescent cell accumulation has been implicated in the pathogenesis of aging-associated diseases, including cancer. The mechanism that prevents the accumulation of senescent cells in aging human organs is unclear. Here, we demonstrate that a virus-immune axis controls the senescent fibroblast accumulation in the human skin. Senescent fibroblasts increased in old skin compared with young skin. However, they did not increase with advancing age in the elderly. Increased CXCL9 and cytotoxic CD4+ T cells (CD4 CTLs) recruitment were significantly associated with reduced senescent fibroblasts in the old skin. Senescent fibroblasts expressed human leukocyte antigen class II (HLA-II) and human cytomegalovirus glycoprotein B (HCMV-gB), becoming direct CD4 CTL targets. Skin-resident CD4 CTLs eliminated HCMV-gB+ senescent fibroblasts in an HLA-II-dependent manner, and HCMV-gB activated CD4 CTLs from the human skin. Collectively, our findings demonstrate HCMV reactivation in senescent cells, which CD4 CTLs can directly eliminate through the recognition of the HCMV-gB antigen.

Increased Regulatory T Cells and Decreased Myeloid-Derived Suppressor Cells Induced by High CCL17 Levels May Account for Normal Incidence of Cancers among Patients with Atopic Dermatitis.

The incidence of cancers in atopic dermatitis (AD) is not increased, although the Th2-dominant environment is known to downregulate tumor immunity. To gain mechanistic insights regarding tumor immunity in AD, we utilized CCL17 transgenic (TG) mice overexpressing CCL17, which is a key chemokine in AD. Tumor formation and lung metastasis were accelerated in CCL17 TG mice when melanoma cells were injected subcutaneously or intravenously. Flow cytometric analysis showed increases in regulatory T cells (Tregs) in lymph nodes in CCL17 TG mice with high mRNA levels of IL-10 and Foxp3 in tumors, suggesting that Tregs attenuated tumor immunity. The frequency of myeloid-derived suppressor cells (MDSCs), however, was significantly decreased in tumors of CCL17 TG mice, suggesting that decreased MDSCs might promote tumor immunity. Expression of CXCL17, a chemoattractant of MDSCs, was decreased in tumors of CCL17 TG mice. Depletion of Tregs by the anti-CD25 antibody markedly reduced tumor volumes in CCL17 TG mice, suggesting that tumor immunity was accelerated by the decrease in MDSCs in the absence of Tregs. Thus, CCL17 attenuates tumor immunity by increasing Tregs and Th2 cells, while it decreases MDSCs through reductions in CXCL17, which may work as a "safety-net" to reduce the risk of malignant tumors in the Th2-dominant environment.

CD147-Cyclophilin a Interactions Promote Proliferation and Survival of Cutaneous T-Cell Lymphoma.

CD147, a transmembrane glycoprotein that belongs to the immunoglobulin superfamily, and cyclophilin A (CypA), one of the binding partners of CD147, are overexpressed in tumor cells and associated with the progression of several malignancies, including both solid and hematological malignancies. However, CD147 and CypA involvement in cutaneous T-cell lymphoma (CTCL) has not been reported. In this study, we examined CD147 and CypA expression and function using clinical samples of mycosis fungoides (MF) and Sézary syndrome (SS) and CTCL cell lines. CD147 and CypA were overexpressed by tumor cells of MF/SS, and CypA was also expressed by epidermal keratinocytes in MF/SS lesional skin. Serum CypA levels were increased and correlated with disease severity markers in MF/SS patients. Anti-CD147 antibody and/or anti-CypA antibody suppressed the proliferation of CTCL cell lines, both in vitro and in vivo, via downregulation of phosphorylated extracellular-regulated kinase 1/2 and Akt. These results suggest that CD147-CypA interactions can contribute to the proliferation of MF/SS tumor cells in both a autocrine and paracrine manner, and that the disruption of CD147-CypA interactions could be a new therapeutic strategy for the treatment of MF/SS.

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.

Increased Expression of Delta-like Ligand 4 in Mycosis Fungoides.

In many malignancies, dysregulation of the Notch pathways, composed of 4 Notch receptors (Notch1-4) and 5 Notch ligands (Jagged1-2, Delta-like ligand-1, 3-4), is associated with their development. In mycosis fungoides, interaction between Notch1 and Jagged1 is known to activate the Notch pathways and promote the proliferation of tumour cells. However, the involvement of other Notch ligands has not been reported. This study investigated the roles of Delta-like ligand 4 in mycosis fungoides. Delta-like ligand 4 mRNA levels in lesional skin of patients with mycosis fungoides were significantly elevated compared with those of normal controls, and correlated with disease-specific mortality. Immunohistochemical staining demonstrated prominent expression of Delta-like ligand 4 on vascular endothelial cells and tumour cells in mycosis fungoides lesional skin. In addition, Delta-like ligand 4 augmented the proliferation of cutaneous T-cell lym-phoma cell lines. These results suggest that enhanced Delta-like ligand 4 expression may contribute directly to the progression of mycosis fungoides through proliferating tumour cells.

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.

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.

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.

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.

High-Risk Non-Melanoma Skin Cancers: Biological and Therapeutic Advances.

Nonmelanoma skin cancers (NMSCs) are the most common cancers, with high-risk NMSCs sharing features such as poor histologic differentiation, invasion into deeper layers, and anatomic location. NMSC includes basal cell carcinoma, cutaneous squamous cell carcinoma, and Merkel cell carcinoma. Herein, the authors describe advances in understanding the genetic mechanisms of malignant transformation and the composition of tumor microenvironment for these cancers. They summarize recent therapeutic advances, including targeted therapy and immunotherapy for NMSCs. Effective skin protection against ultraviolet radiation-induced carcinogenesis remains an urgent unmet need for NMSC prevention. The authors highlight immune-based interventions as novel strategies to address this need.

Combined PD-1, BRAF and MEK inhibition in BRAFV600E colorectal cancer: a phase 2 trial.

While BRAF inhibitor combinations with EGFR and/or MEK inhibitors have improved clinical efficacy in BRAFV600E colorectal cancer (CRC), response rates remain low and lack durability. Preclinical data suggest that BRAF/MAPK pathway inhibition may augment the tumor immune response. We performed a proof-of-concept single-arm phase 2 clinical trial of combined PD-1, BRAF and MEK inhibition with sparatlizumab (PDR001), dabrafenib and trametinib in 37 patients with BRAFV600E CRC. The primary end point was overall response rate, and the secondary end points were progression-free survival, disease control rate, duration of response and overall survival. The study met its primary end point with a confirmed response rate (24.3% in all patients; 25% in microsatellite stable patients) and durability that were favorable relative to historical controls of BRAF-targeted combinations alone. Single-cell RNA sequencing of 23 paired pretreatment and day 15 on-treatment tumor biopsies revealed greater induction of tumor cell-intrinsic immune programs and more complete MAPK inhibition in patients with better clinical outcome. Immune program induction in matched patient-derived organoids correlated with the degree of MAPK inhibition. These data suggest a potential tumor cell-intrinsic mechanism of cooperativity between MAPK inhibition and immune response, warranting further clinical evaluation of optimized targeted and immune combinations in CRC. ClinicalTrials.gov registration: NCT03668431.

Alarmin Cytokines as Central Regulators of Cutaneous Immunity.

Skin acts as the primary interface between the body and the environment. The skin immune system is composed of a complex network of immune cells and factors that provide the first line of defense against microbial pathogens and environmental insults. Alarmin cytokines mediate an intricate intercellular communication between keratinocytes and immune cells to regulate cutaneous immune responses. Proper functions of the type 2 alarmin cytokines, thymic stromal lymphopoietin (TSLP), interleukin (IL)-25, and IL-33, are paramount to the maintenance of skin homeostasis, and their dysregulation is commonly associated with allergic inflammation. In this review, we discuss recent findings on the complex regulatory network of type 2 alarmin cytokines that control skin immunity and highlight the mechanisms by which these cytokines regulate skin immune responses in host defense, chronic inflammation, and cancer.

Increased expression of squamous cell carcinoma antigen 1 and 2 in mycosis fungoides and Sézary syndrome

Background: Squamous cell carcinoma antigen (SCCA) was originally isolated as tumour-specific antigens in uterine cervix carcinoma. These comprise two similar proteins, SCCA1 and SCCA2, and both are induced by type 2 cytokines such as interleukin (IL)-4 and IL-13. The involvement of these antigens in atopic dermatitis has been reported, however, the role in mycosis fungoides (MF) and Sézary syndrome (SS), which are also linked with type 2 cytokines, remains to be seen. Objectives: This study investigated a possible association between SCCA1/2 and MF/SS. Materials & Methods: We compared serum levels of SCCA1/2 between MF/SS patients and healthy controls. We also examined the correlation between serum SCCA1/2 levels in MF/SS patients and clinical disease markers. The expression of SCCA1/2 in skin samples was examined by immunohistochemistry. Results: The serum levels of SCCA1/2 in MF/SS patients were significantly higher than those in normal controls and correlated with clinical disease markers. Immunohistochemical staining showed upregulated expression of SCCA1/2 in MF/SS lesional skin. Conclusion: Enhanced SCCA1/2 expression may contribute to the progression of MF/SS. Measurement of serum SCCA1/2 levels may become a useful tool to evaluate the progression or therapeutic effects of MF/SS.

Unusual type of scleromyxedema with multiple subcutaneous nodules, IgM-λ paraproteinemia, and scleroderma-like microangiopathy.

Scleromyxedema is a mysterious cutaneous mucinosis of unknown etiology. Various types of scleromyxedema variant have been reported, which often give us a clue to understand the key aspects of this disease. Here, we describe a woman with highly unusual type of scleromyxedema. In addition to the rare manifestations of multiple subcutaneous nodules and IgM-λ paraproteinemia, our patient showed several characteristic symptoms of scleroderma such as shortened nails and fingertips, sclerodactyly, and bone resorption of fingertips and mandibles as a result of peripheral circulatory insufficiency, although this disease is known to be pathophysiologically different from scleroderma. A skin biopsy revealed cutaneous microvascular stenosis and occlusion due to intravascular mucin deposition and fibrotic changes, suggesting that scleromyxedema potentially develops peripheral circulatory disorders and other vascular involvement. The subcutaneous nodules were responsive to high-dose intravenous immunoglobulin. Scleromyxedema can represent a wide variety of systemic involvement, and therefore, we should pay attention to those symptoms as well as skin lesions.

Mycosis fungoides and Sézary syndrome tumor cells express epidermal fatty acid-binding protein, whose expression decreases with loss of epidermotropism.

Fatty acid binding protein (FABP) is a family of transport proteins for fatty acid (FA). Epidermal FABP (E-FABP) is highly expressed by resident memory T cells (TRM ) in the skin. It supports the uptake of exogenous FA for long-term survival of skin TRM . Mycosis fungoides (MF) is regarded as malignancy of skin TRM . In this study, we investigated E-FABP expression in psoriasis vulgaris (PV), atopic dermatitis (AD), MF, and Sézary syndrome (SS). E-FABP mRNA levels in PV were much higher than those in healthy controls. E-FABP mRNA levels in AD and MF/SS lesional skin were also significantly higher than those of normal skin. By immunohistochemical staining, E-FABP was positive in MF/SS lesional skin. Interestingly, E-FABP was stained positive in epidermotropic lymphoid cells in patch, plaque, and erythrodermic lesions of MF/SS, suggesting that a part of tumor cells expressed E-FABP. In tumorous lesions, however, most dermal tumor cells were negative for E-FABP. Immunohistochemical staining using patch/plaque lesions and tumorous lesions from the same patients also revealed that E-FABP expression decreased in tumorous lesions. Our study has suggested that MF/SS tumor cells express E-FABP, whose expression decreases with loss of epidermotropism.

Primary cutaneous γδ T-cell lymphoma with unusual immunophenotype: A case report and review of published work.

Primary cutaneous γδ T-cell lymphoma (CGD-TCL) is a rare form of primary cutaneous lymphoma. The histopathological features of CGD-TCL are still unclear because of its rarity. Here, we report a case of a 77-year-old Japanese man who presented with a 9-month history of erythematous plaques on his left forearm. Skin biopsy specimens revealed the infiltration of atypical medium/large-sized lymphocytes from the epidermis to the deep dermis. Atypical lymphocytes were positive for CD3, CD5, CD8 and Vδ1, and negative for CD4, CD7, CD56, EBER-ISH, intracellular antigen-1, granzyme B and perforin. CD30 was partially expressed. We also reviewed 246 cases of CGD-TCL from the published work. CD4- CD8- double-negative cases were 113 of 196 cases (57.6%), followed by CD4- CD8+ cases (52/196, 26.5%). CD5 was expressed in 25.8% of the cases (34/132). At least one cytotoxic molecule marker was expressed in 150 of 160 cases (93.8%). Some cases showed an indolent clinical course, especially in mycosis fungoides-like CGD-TCL cases. CD5 positivity and lack of cytotoxic molecule expression could be associated with a better prognosis. In addition, CD30 expression was found in approximately half of CGD-TCL cases (51/112 cases), suggesting that brentuximab vedotin could be a good treatment option for such patients. Further studies with more cases with detailed clinical and pathological information are necessary to elucidate the etiology and prognostic markers of this entity.

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.