Leukemic Cutaneous T-cell Lymphoma Research Articles

Evaluation of the Cellular Resistance Process in Treated Cells Via Extracorporeal Photopheresis.

Introduction: Extracorporeal photopheresis (ECP) is a therapeutic method applied against some diseases such as cancers. Using 8-methoxypsoralen (8-MOP) and UVA radiation in ECP is associated with achievement in the treatment of patients with leukemic cutaneous T-cell lymphoma (CTCL). Evaluation of cellular resistance versus ECP is the aim of this study. Methods: Data were downloaded from the Gene Expression Omnibus (GEO) database and were analyzed via the GEO2R program. The significant DEGs were assessed via protein-protein interaction (PPI) network analysis by using the STRING database and Cytoscape software. The critical genes were evaluated via gene ontology by using the ClueGO application of Cytoscape software. The identified biological processes were determined and analyzed. Results: Fifty-seven significant DEGs were determined. The main connected component of the PPI network including 32 queried significant DEGs plus 50 first neighbors was constructed. Nineteen histones as critical nodes were assessed via gene ontology, and "nucleosome organization" was pointed out as the crucial biological process. Finally, 15 histones from H2A, H2B, and H3 histone families were identified as the key genes that are involved in the resistance property of the treated cells. Conclusion: In conclusion, 15 members of H2A, H2B, and H3 families (especially H2A family) were considered as the origin of resistance versus ECP treatment. It is concluded that sensitivity to ECP treatment depends on gross molecular events which are involved in the functions of histones.

FISH Panel for Leukemic Cutaneous T-Cell Lymphoma: Extended Patient Cohort Correlation with Blood Involvement and Clinical Outcomes

The genomic basis of cutaneous T-cell lymphoma has been characterized by gene copy number alterations and genomic sequencing, but there are few clinical tests that are being widely used to inform the diagnosis and prognosis of leukemic cutaneous T-cell lymphoma that may arise as a progression from mycosis fungoides or de novo as Sézary syndrome. An 11-gene FISH panel of TP53, RB1, DNMT3A, FAS, ZEB1, ARID1A, ATM, and CDKN2A deletions and MYC, signal transducer and activator of transcription gene (STAT)3/5B, and CARD11 amplifications was previously found to encapsulate >95% of gene copy number variations in leukemic cutaneous T-cell lymphoma. Through a retrospective analysis of patients with leukemic cutaneous T-cell lymphoma seen at the Yale Cancer Center from 2014 to 2020, we gathered the relevant genes as they became available and correlated them to factors with prognostic relevance as a proof of concept to show the potential utility in further developing a limited gene panel for prognosis. In this study, we show that the abnormal FISH results show an association with clinically relevant factors (blood stage, CD4:8 ratio, and percentage blood involvement) and have a nonsignificant statistical trend (>90%) toward correlation with overall survival. In addition, the previous cost-effective panels were signal transducer and activator of transcription (STAT)3/5B, MYC, TP53, and ARID1A. We now suggest adding RB1 and ZEB1 on the basis of our findings.

Blocking STAT3/5 through direct or upstream kinase targeting in leukemic cutaneous T-cell lymphoma.

Leukemic cutaneous T-cell lymphomas (L-CTCL) are lymphoproliferative disorders of skin-homing mature T-cells causing severe symptoms and high mortality through chronic inflammation, tissue destruction, and serious infections. Despite numerous genomic sequencing efforts, recurrent driver mutations have not been identified, but chromosomal losses and gains are frequent and dominant. We integrated genomic landscape analyses with innovative pharmacologic interference studies to identify key vulnerable nodes in L-CTCL. We detected copy number gains of loci containing the STAT3/5 oncogenes in 74% (n=17/23) of L-CTCL, which correlated with the increased clonal T-cell count in the blood. Dual inhibition of STAT3/5 using small-molecule degraders and multi-kinase blockers abolished L-CTCL cell growth invitro and exvivo, whereby PAK kinase inhibition was specifically selective for L-CTCL patient cells carrying STAT3/5 gains. Importantly, the PAK inhibitor FRAx597 demonstrated encouraging anti-leukemic activity invivo by inhibiting tumor growth and disease dissemination in intradermally xenografted mice. We conclude that STAT3/5 and PAK kinase interaction represents a new therapeutic node to be further explored in L-CTCL.

BioIns-PO-09 - Elevated A-to-I RNA editing in leukemic cutaneous T-cell lymphoma

BioIns-PO-09 - Elevated A-to-I RNA editing in leukemic cutaneous T-cell lymphoma

BioIns-O-10 - Boost of innate immunity cytokines as biomarkers of response to extracorporeal photopheresis in leukemic cutaneous T-cell lymphoma patients

BioIns-O-10 - Boost of innate immunity cytokines as biomarkers of response to extracorporeal photopheresis in leukemic cutaneous T-cell lymphoma patients

Bio-P-13 - Boost of innate immunity cytokines as biomarkers of response to extracorporeal photopheresis in leukemic cutaneous T-cell lymphoma patients

Extracorporeal photopheresis (ECP) emerged as a systemic first-line therapy in leukemic cutaneous T-cell lymphoma (L-CTCL) and is now being implemented in a variety of T-cell-mediated diseases. Although ECP has been used for nearly 30 years, the mechanisms of its efficacy are not sufficiently understood and biomarkers for response are lacking. We aim to investigate the immunomodulatory effects of ECP on cytokine secretion patterns in patients with L-CTCL. A total of 22 L-CTCL patients and 15 healthy donors (HDs) were retrospectively enrolled in this study. Concentrations of 16 cytokines were simultaneously quantified by using multiplex bead-based immunoassays. First, the result revealed distinct cytokine patterns between L-CTCLs and HDs. We observed significant loss of TNFa and IL-8, and significant increase of IL-9 and IL-13 in serums of L-CTCL patients compare to HDs. As a next step, L-CTCL patients who received ECP were classified to responder and non-responder to treatment according to their quantitative reduction of malignant burden in the blood. We evaluated cytokine levels in culture supernatants from patient peripheral blood mononuclear cells (PBMCs) at baseline and over 27 weeks after ECP. Strikingly, PBMCs purified from ECP responders released statistically higher concentration of innate immunity cytokines such as IL-1a, IL-1b, GM-CSF and TNFα in comparison with ECP non-responders. In parallel, clinical observations documented complete clearance of erythema, reduction of malignant clonal T cells in the blood, and a potent boost of relevant innate immunity cytokines in individual L-CTCL patients. To conclude, our results demonstrated that ECP stimulates innate immune network, and this implied how ECP facilitates redirection of tumor-biased immunosuppressive microenvironment toward active anti-tumor responses. The alteration of TNFα, IL-1a, IL-1b and GM-CSF can possibly be used as biomarkers of response to ECP in leukemic CTCL patients.

Monitoring malignant T-cell clones by direct TCR expression assay in patients with leukemic cutaneous T-cell lymphoma during extracorporeal photopheresis.

Accurate assessment of malignant T-cell clones in patients with leukemic cutaneous T-cell lymphoma (L-CTCL) is crucial for diagnosis, treatment, and monitoring disease. Although multiple approaches to quantitate malignant T-cell clones have been reported, a cost-effective assay with broad coverage is not available. We report a NanoString-nCounter-Technology-based direct TCR expression assay (DTEA) that was previously developed to quantify both TCR-Vα and TCR-Vβ usages after adoptive immunotherapy. This study was performed to test the effectiveness of DTEA in assessing malignant T-cell clones in L-CTCL patients. Total RNAs extracted from peripheral blood mononuclear cells of patients before starting extracorporeal photopheresis (ECP) (n=15) and during therapy at 3months and 6 months (n=12) were used for DTEA, with customized probes for 45 TCR-Vα and 46 TCR-Vβ family members. At baseline, DTEA detected TCR-Vβ clones in all 15 patients (100%) compared to flow cytometry that detected TCR-Vβ clones in 9 of 13 patients (69.2%). In addition to predominant TCR-Vβ clones, DTEA also detected additional TCR-Vβ clones in 8 of 15 patients (53.3%). Furthermore, DTEA simultaneously identified clonal TCR-Vα usages, which allowed us to pair TCR-Vα and TCRVβ usages by malignant T-cells and identify diversified clonotypes. Changes in the relative frequencies of clonal TCR-Vβ and TCRVα usages over therapy were consistent with patients' clinical responses. Our results indicate that DTEA can effectively assess malignant T-cell clones by detecting clonal TCR-Vα and TCR-Vβ usages. By providing a global view of TCR repertoires, DTEA may also help us understand the origin(s) of malignant T-cells and pathogenesis of CTCL.

Branched evolution and genomic intratumor heterogeneity in the pathogenesis of cutaneous T-cell lymphoma

AbstractMycosis fungoides (MF) is a slowly progressive cutaneous T-cell lymphoma (CTCL) for which there is no cure. In the early plaque stage, the disease is indolent, but development of tumors heralds an increased risk of metastasis and death. Previous research into the genomic landscape of CTCL revealed a complex pattern of >50 driver mutations implicated in more than a dozen signaling pathways. However, the genomic mechanisms governing disease progression and treatment resistance remain unknown. Building on our previous discovery of the clonotypic heterogeneity of MF, we hypothesized that this lymphoma does not progress in a linear fashion as currently thought but comprises heterogeneous mutational subclones. We sequenced exomes of 49 cases of MF and identified 28 previously unreported putative driver genes. MF exhibited extensive intratumoral heterogeneity (ITH) of a median of 6 subclones showing a branched phylogenetic relationship pattern. Stage progression was correlated with an increase in ITH and redistribution of mutations from stem to clades. The pattern of clonal driver mutations was highly variable, with no consistent mutations among patients. Similar intratumoral heterogeneity was detected in leukemic CTCL (Sézary syndrome). Based on these findings, we propose a model of MF pathogenesis comprising divergent evolution of cancer subclones and discuss how ITH affects the efficacy of targeted drug therapies and immunotherapies for CTCL.

CD30+ leukemic cutaneous T-cell lymphoma

To the Editor: CD30 is a tumor necrosis factor receptor involved in regulating apoptosis and proliferation of CD30+ tumor cells.1 CD30+ T cells are primarily expressed in conditions such as primary cutaneous CD30+ T-cell lymphoproliferative disorders and some peripheral T-cell lymphomas, and they can potentially be expressed in any type of cutaneous T-cell lymphoma (CTCL).2-4 However, CD30 expansion on the leukemic cells of patients with CTCL or Sézary syndrome is rare, and little is known regarding the natural history and prognosis of patients with leukemic CTCL expressing this cell type.

CD209+ monocyte‐derived myeloid dendritic cells were increased in patients with leukemic cutaneous T‐cell lymphoma undergoing extracorporeal photopheresis via the CELLEXTM system

We previously reported that myeloid dendritic cells (mDC) were increased in patients with leukemic cutaneous T-cell lymphoma (L-CTCL) following extracorporeal photopheresis (ECP) using the Therakos UVAR XTS™ system. We now assessed monocyte-derived mDCs (Mo-DCs) in L-CTCL patients treated with the CELLEXTM photopheresis system. CD209, a transmembrane receptor, was used to define Mo-DCs. Peripheral blood samples from baseline pre-ECP and at Day 2, 1month, 3months, and 6months post-ECP were analyzed by flow cytometry for Lin- HLA-DR+ CD123+ plasmacytoid dendritic cells (pDCs), Lin- HLA-DR+ CD11c+ mDCs, and CD209+ mDCs. The expression of CD209 mRNA was assessed by real-time PCR. At baseline, 7 of 19 patients had lower than normal mDCs, and all patients had lower than normal CD209+ mDCs in peripheral blood mononuclear cells (0.005% in patients, n=19, vs 0.50% in healthy donors, n=7, P<.0001). The CD209+ mDC numbers only accounted for 3.28% out of total mDCs in patients compared with 66.51% in healthy donors. After treatment, the CD209+ mDC numbers showed increasing trends in patients. The average absolute numbers of CD209+ mDCs went up by 4.8-fold at 3months (n=10, P=.103) and by 6.4-fold at 6months (n=9, P=.100). CD209 mRNA expression went up in two patients responsive to therapy, parallel to CD209+ mDC numbers. L-CTCL patients achieved 70% overall clinical response rate (7/10) following ECP therapy with the CELLEXTM system. Our results suggest that the CELLEXTM photopheresis system is effective for treating L-CTCL patients like the UVAR XTS™ system, and in vivo-generated Mo-DCs increase following ECP.

Blood transcriptional profiling reveals IL-1 and integrin signaling pathways associated with clinical response to extracorporeal photopheresis in patients with leukemic cutaneous T-cell lymphoma.

ABSTRACTExtracorporeal photopheresis (ECP) is a frontline therapy for patients with leukemic cutaneous T-cell lymphoma (L-CTCL), but its mechanisms of action are not fully understood. This study was to explore the molecular mechanisms underlying clinical response versus non-response in patients with L-CTCL. We performed blood transcriptional profiling of ten L-CTCL patients at Day 2 and 1 month post- ECP compared to pre-ECP baseline using Agilent Whole Human Genome Microarray technology. Differentially expressed genes (DEGs) between five clinically-responsive patients and five clinically-resistant patients were cross-compared. Higher numbers of genes were modulated in responders than non-responders after ECP at both Day 2 and 1 month, with two thirds of DEGs down-regulated. The down-regulated DEGs at 1 month post-ECP were related to inflammatory, immune and/or stress responses, platelet functions, and chromatin remodeling. Upregulated DEGs were mainly related to functions of the nucleolus. Pathway analysis revealed that integrin and IL-1 signaling pathways were the top pathways affected in responders, which were minimally affected in non-responders. The top upstream transcription regulators affected were IL1B, EGR1, FAS, and TGFB1. Our results suggest that the modulation of cell adhesion and suppression of IL-1β induced inflammation may underlie the efficacy of ECP in L-CTCL.

1009 Optimizing immunological reinvigoration in leukemic cutaneous T-cell lymphoma through use of multiple immune checkpoint inhibitors

We have previously demonstrated that malignant T-cells in leukemic CTCL (L-CTCL) may simultaneously express mulitple immune checkpoint molecules, including PD-1, CTLA4 and TIGIT, possibly contributing to immune evasion and immune exhaustion and these may also have relevance to prognosis. The ability to block signaling of these molecules is likely to be beneficial to clinical outcome which is supported by preliminary data from trials using anti-PD-1 therapy for advanced CTCL. In this study we assessed the use of multiple immune checkpoint inhibitors on the proliferation and Th1 cytokine production of CD4 and CD8 T-cells of patients with L-CTCL. Purified, freshly isolated lymphocytes from 22 patients with L-CTCL were cultured with varying concentrations of anti-PD-1 or anti-TIGIT for 96 hours with assessment of T-cell proliferation, expression of cytolytic molecules and production of IL-2 and interferon gamma. A significant increase in proliferation of both CD4 and CD8 T-cells in response to anti-PD-1 was noted among the cells of 8 patients while the response to TIGIT resulted in increased proliferation of T-cells from 6 patients. Exposure to anti-PD-1 resulted in significant increases in IL-2 production by the cells of 9 patients and increased production of interferon gamma by 5 patients. Anti-TIGIT increased IL-2 production by 5 patients while interferon gamma production was increased among the cells of 4 patients. Combination blockade further enhanced immune responses of 6 patients. These results indicate that different immune checkpoint inhibitors may exert beneficial enhancement of T-cell proliferation and cytokine production among patients with leukemic CTCL and variable responses to each supports the use of combination checkpoint inhibition to improve clinical outcomes.

Preclinical Studies Support Combined Inhibition of BET Family Proteins and Histone Deacetylases as Epigenetic Therapy for Cutaneous T-Cell Lymphoma

Advanced-stage cutaneous T-cell lymphoma (CTCL) is usually a fatal malignancy despite optimal use of currently available treatments. In this preclinical study of novel CTCL therapy, we performed in vitro and ex vivo experiments to determine the efficacy of combination treatment with a panel of BET bromodomain inhibitors (BETi) (JQ1, OTX015, CPI-0610, I-BET762) and HDAC inhibitors (HDACi) (SAHA/Vorinostat, Romidepsin). BETi/HDACi combinations were synergistic (combination index <1) against cell viability and induced G0/G1 cell cycle arrest. Apoptosis was uniformly enhanced. From a mechanistic standpoint, proliferative drivers c-Myc, Cyclin D1, NFkB, and IL-15Rα were reduced. Inhibitory CDKN1A was increased. CDKN1B, IL-7R, IL-17Rα, STAT3, and STAT5 alterations varied. There were significant increases in extrinsic apoptotic pathway death receptors and ligands (FasL, DR4, DR5, TRAIL, and TNFR1). At clinically tolerable levels of single agents, Romidepsin (1 nM) + OTX015 (125 nM) induced the greatest apoptosis (60%_80%) at 96 hours. Ex vivo studies of leukemic CTCL cells obtained from patients with Sezary syndrome also showed higher levels of apoptosis (about 60%-90%) in response to combination treatments relative to single agents. In contrast, combination treatment of normal CD4+ T cells induced only minimal apoptosis (<10%). Our findings show that the mechanism of action of BETi/HDACi therapy in CTCL involves induction of both cell cycle arrest and apoptosis with reduced proliferative drivers and enhanced expression of apoptotic extrinsic pathway death receptors and ligands. Relative to single agents, the superior anti-CTCL effects of BETi/HDACi combinations in vitro and ex vivo provide a rationale for clinical trials exploring their efficacy as therapy for CTCL.

Epigenetically Enhanced PDT Induces Significantly Higher Levels of Multiple Extrinsic Pathway Apoptotic Factors than Standard PDT, Resulting in Greater Extrinsic and Overall Apoptosis of Cutaneous T-cell Lymphoma.

Aminolevulinate-based photodynamic therapy (ALA-PDT) selectively eliminates diseased tissues primarily through the induction of intrinsic apoptotic pathway. ALA-PDT is a first-line therapy for actinic keratosis, however, it is less effective for cutaneous T-cell lymphoma (CTCL). We have previously demonstrated that the resistance of CTCL to apoptosis correlates with decreased expression of death receptors such as FAS, and that methotrexate functions as an epigenetic regulator that reestablishes the susceptibility of CTCL to extrinsic pathway apoptosis. We showed previously that MTX augments the effectiveness of PDT by sensitizing cells to apoptosis by induction of apoptotic factors, a process we call "epigenetically enhanced" PDT (ePDT). Here, in CTCL cell lines, leukemic CTCL cells, and normal blood T cells, we analyzed multiple components of the FAS, TRAIL, and TNF families using multispectral imaging of immunostained cytopreparations, a quantitative technique with five-fold greater sensitivity than standard immunocytology. ePDT induced significantly greater FAS, FASL, TRAIL-R1 & -R2, and TNFα levels than standard PDT. This correlated with significantly greater induction of extrinsic pathway apoptosis and/or overall apoptosis in all CTCL samples. There was no appreciable effect on normal T cells. These data set the stage for clinical trials of ePDT as a novel localized treatment of CTCL.

Prognostic Implications of Blood B Ratings for Erythrodermic Cutaneous T cell Lymphoma

Objective: The magnitude of blood involvement in cutaneous T cell lymphoma (CTCL) has prognostic significance. Several groups have proposed hematologic criteria for B ratings for use in clinical staging of CTCL, but in practice B ratings are only relevant for the staging of erythrodermic CTCL without lymph node or visceral involvement, i.e., T4N0-2M0B0 defines sub-stage IIIA, T4N0-2M0B1 defines sub-stage IIIB and T4N0-2M0B2 defines sub-stage IVA1. This retrospective study examines the effect of various B rating criteria on prognoses of patients with erythrodermic CTCL. Methods: At initial presentation, 152 patients diagnosed with E-CTCL had quantitative Sezary cell counts performed on blood smears and CD4+/CD8- ratios determined in the blood by flow cytometry. In addition, 39 patients had percentages of CD4+CD26- and CD4+CD7- lymphocytes directly measured. The Kaplan-Meier method and Cox proportional hazards model were used to estimate mean overall and CTCL-specific survival and to compare survival curves of sub-stages of erythrodermic CTCL. Results: With B2 rating defined as absolute Sezary cell counts ≥ 1.0 K/μL or CD4+/CD8- ratio ≥ 10, a better separation of survival curves between sub-stages IIIA and IIIB was observed if the threshold for B1 was defined as Sezary cells ≥ 20% and CD4+/CD8- ratio defined as ≥ 4 plus confirmation of blood involvement. With either criterion, the survival of patients at sub-stages IVA1 and IVA2 were not statistically different. There was also a suggestion that percentage of CD4+CD26- or CD4+CD7- cells (which ever was higher) might be used to define B1 and B2 thresholds (≥ 30% and ≥ 60%, respectively) as an alternative to absolute counts. Maximum CD4+CD26-/CD4+CD7- ≥ 30% plus confirmation also might provide a hematologic definition of leukemic CTCL. Conclusion: Additional studies on larger number of patients and evaluation with other measures of blood tumor burden are indicated.

Genetic rearrangements result in altered gene expression and novel fusion transcripts in Sézary syndrome.

Sézary syndrome (SS) is an aggressive, leukemic cutaneous T-cell lymphoma variant. Molecular pathogenesis of SS is still unclear despite many studies on genetic alterations, gene expression and epigenetic regulations. Through whole genome and transcriptome next generation sequencing nine Sézary syndrome patients were analyzed in terms of copy number variations and rearrangements affecting gene expression. Recurrent copy number variations were detected within 8q (MYC, TOX), 17p (TP53, NCOR1), 10q (PTEN, FAS), 2p (DNMT3A), 11q (USP28), 9p (CAAP1), but no recurrent rearrangements were identified. However, expression of five genes involved in rearrangements (TMEM244, EHD1, MTMR2, RNF123 and TOX) was altered in all patients. Fifteen rearrangements detected in Sézary syndrome patients and SeAx resulted in an expression of new fusion transcripts, nine of them were in frame (EHD1-CAPN12, TMEM66-BAIAP2, MBD4-PTPRC, PTPRC-CPN2, MYB-MBNL1, TFG-GPR128, MAP4K3-FIGLA, DCP1A-CCL27, MBNL1-KIAA2018) and five resulted in ectopic expression of fragments of genes not expressed in normal T-cells (BAIAP2, CPN2, GPR128, CAPN12, FIGLA). Our results not only underscored the genomic complexity of the Sézary cancer cell genome but also showed an unpreceded large variety of novel gene rearrangements resulting in fusions transcripts and ectopically expressed genes.

654 Monitoring malignant T-cell clones by direct TCR expression assay in patients with leukemic cutaneous T-cell lymphoma over extracorporeal photopheresis

654 Monitoring malignant T-cell clones by direct TCR expression assay in patients with leukemic cutaneous T-cell lymphoma over extracorporeal photopheresis

312 Epigenetically-enhanced PDT (ePDT) induces significantly higher levels of multiple extrinsic pathway apoptotic factors than conventional PDT, resulting in greater extrinsic and overall apoptosis of CTCL

Conventional photodynamic therapy with aminolevulinate (ALA-PDT) selectively induces apoptosis in diseased cells primarily through the caspase 9-mediated intrinsic (mitochondrial) pathway and is highly effective for treating actinic keratoses. However, it is less effective for cutaneous T-cell lymphoma (CTCL). This failure may be related to the fact that although conventional PDT increases FASL expression via the JNK/c-Jun pathway, this same pathway can inhibit FAS expression. Our prior work showed that the apoptotic resistance of CTCL correlates with low expression of death receptors like FAS, and that methotrexate can upregulate FAS by inhibiting methylation of its promoter, acting as an epigenetic derepressor that restores the susceptibility of FAS-low CTCL to caspase 8-mediated extrinsic pathway apoptosis. We hypothesized that the limited efficacy of conventional PDT in CTCL is due to dysfunctional extrinsic apoptosis, and showed that epigenetic regulators like MTX will significantly increase the efficacy of PDT by sensitizing the targeted cells to apoptosis via up-regulation of death receptors such as FAS, a concept we refer to as epigenetically-enhanced PDT (ePDT) (Salva KA, Wood GS. Photochem Photobiol 91: 1444-51, 2015). Here, in CTCL lines, leukemic CTCL cells and normal blood T cells, we analyzed multiple components of the FAS, TRAIL and TNF families in vitro and ex vivo with multispectral imaging of immunostained cells, a quantitative method 5x more sensitive than standard immunocytology. Relative to conventional PDT, ePDT induced significantly greater FAS, FASL, TRAIL-R1 & -R2, and TNFa. This correlated with significantly greater induction of markers of extrinsic pathway apoptosis (cleaved caspase 8) and overall apoptosis (cleaved caspase 3) in all CTCL samples. There was no appreciable effect on normal T cells. These findings provide a rationale for clinical trials of ePDT for local therapy of CTCL.

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.

The expression of CADM1/TSLC1 in leukemic cutaneous T-cell lymphoma: A possible diagnostic marker for Sézary syndrome

The expression of CADM1/TSLC1 in leukemic cutaneous T-cell lymphoma: A possible diagnostic marker for Sézary syndrome