MHC-I upregulation safeguards neoplastic T cells in the skin against NK cell-mediated eradication in mycosis fungoides.

Cancer-associated immune dysfunction is a major challenge for effective therapies. The emergence of antibodies targeting tumor cell-surface antigens led to advancements in the treatment of hematopoietic malignancies, particularly blood cancers. Yet their impact is constrained against tumors of hematopoietic origin manifesting in the skin. In this study, we employ a clonality-supervised deep learning methodology to dissect key pathological features implicated in mycosis fungoides, the most common cutaneous T-cell lymphoma. Our investigations unveil the prominence of the IL-32ß-major histocompatibility complex (MHC)-I axis as a critical determinant in tumor T-cell immune evasion within the skin microenvironment. In patients' skin, we find MHC-I to detrimentally impact the functionality of natural killer (NK) cells, diminishing antibody-dependent cellular cytotoxicity and promoting resistance of tumor skin T-cells to cell-surface targeting therapies. Through murine experiments in female mice, we demonstrate that disruption of the MHC-I interaction with NK cell inhibitory Ly49 receptors restores NK cell anti-tumor activity and targeted T-cell lymphoma elimination in vivo. These findings underscore the significance of attenuating the MHC-I-dependent immunosuppressive networks within skin tumors. Overall, our study introduces a strategy to reinvigorate NK cell-mediated anti-tumor responses to overcome treatment resistance to existing cell-surface targeted therapies for skin lymphoma.

Th17-associated cytokines IL-17 and IL-23 in inflamed skin of Darier disease patients as potential therapeutic targets.

Darier disease (DD) is a rare, inherited multi-organ disorder associated with mutations in the ATP2A2 gene. DD patients often have skin involvement characterized by malodorous, inflamed skin and recurrent, severe infections. Therapeutic options are limited and inadequate for the long-term management of this chronic disease. The aim of this study was to characterize the cutaneous immune infiltrate in DD skin lesions in detail and to identify new therapeutic targets. Using gene and protein expression profiling assays including scRNA sequencing, we demonstrate enhanced expression of Th17-related genes and cytokines and increased numbers of Th17 cells in six DD patients. We provide evidence that targeting the IL-17/IL-23 axis in a case series of three DD patients with monoclonal antibodies is efficacious with significant clinical improvement. As DD is a chronic, relapsing disease, our findings might pave the way toward additional options for the long-term management of skin inflammation in patients with DD.

Boost of innate immunity cytokines as biomarkers of response to extracorporeal photopheresis in patients with leukaemic cutaneous T-cell lymphoma.

BACKGROUND: Extracorporeal photopheresis (ECP) has emerged as a systemic first-line immunomodulatory therapy in leukaemic cutaneous T-cell lymphoma (L-CTCL) and is now beginning to be utilized in other T-cell-mediated diseases. Although ECP has been used for nearly 30 years, its mechanisms of action are not sufficiently understood, and biomarkers for response are scarce. OBJECTIVES: We aimed to investigate the immunomodulatory effects of ECP on cytokine secretion patterns in patients with L-CTCL, to help elucidate its mechanism of action. METHODS: A total of 25 patients with L-CTCL and 15 healthy donors (HDs) were enrolled in this retrospective cohort study. Concentrations of 22 cytokines were simultaneously quantified by using multiplex bead-based immunoassays. Neoplastic cells in patients' blood were evaluated by flow cytometry. RESULTS: Firstly, we observed a distinct cytokine profile pattern difference between L-CTCLs and HDs. There was a significant loss of tumour necrosis factor (TNF)-α, and significant increase of interleukins (IL)-9, IL-12 and IL-13 in the sera of patients with L-CTCL compared with HDs. Secondly, patients with L-CTCL who received ECP were classified as treatment responders and nonresponders according to the quantitative reduction of malignant burden in their blood. We evaluated cytokine levels in culture supernatants from patients' peripheral blood mononuclear cells (PBMCs) at baseline and 27 weeks after ECP initiation. Strikingly, PBMCs purified from ECP responders released statistically higher concentrations of innate immune cytokines IL-1α, IL-1ß, granulocyte-macrophage colony-stimulating factor (GM-CSF) and TNF-α in comparison with ECP nonresponders. In parallel, responders showed clearance of erythema, reduction of malignant clonal T cells in the blood, and a potent boost of relevant innate immune cytokines in individual patients with L-CTCL. CONCLUSIONS: Taken together, our results demonstrate that ECP stimulates the innate immune network, and facilitates redirection of the tumour-biased immunosuppressive microenvironment towards proactive antitumour immune responses. The alterations of IL-1α, IL-1ß, GM-CSF and TNF-α can be used as biomarkers of response to ECP in patients with L-CTCL.

Enhancement of antibody-dependent cellular cytotoxicity is associated with treatment response to extracorporeal photopheresis in Sézary syndrome.

Sézary syndrome (SS) is a rare, leukemic type of cutaneous T-cell lymphoma (CTCL), for which extracorporeal photopheresis (ECP) is a first-line therapy. Reliable biomarkers to objectively monitor the response to ECP in patients with SS are missing. We examined the quantitative and qualitative impact of ECP on natural killer (NK) cell activity in SS patients, and especially their functional ability for antibody-dependent cell-mediated cytotoxicity (ADCC). Further, we addressed the question whether the magnitude of the effect on ADCC can be associated with the anti-cancer efficacy of ECP in SS patients. We assessed numbers of NK cells, ADCC activity, and treatment response based on blood tumor staging in a cohort of 13 SS patients (8 women, 5 men) treated with ECP as a first-line therapy. Blood samples were collected before treatment start and after an average of 9 months of uninterrupted ECP treatment. NK cell numbers were reduced in SS patients compared to healthy individuals and showed a tendency of recovery after long-term ECP treatment, independent of the clinical response to treatment. Patients with marginal increase (≤1.5 AU-fold) or lack of increase in ADCC activity failed to respond clinically to treatment, while patients with an increased ADCC activity showed a reduction in blood tumor burden. NK-mediated ADCC is selectively enhanced and might be a mechanism underlying the effect of ECP while in addition it can possibly serve as a reliable biomarker to objectively monitor response to ECP in patients with SS.

Selective inhibition of HDAC6 sensitizes cutaneous T-cell lymphoma to PI3K inhibitors.

Histone deacetylase (HDAC) inhibitors, approved for the treatment of cutaneous T-cell lymphoma (CTCL), are non-selective agents associated with an unsatisfactory response and considerable side-effects. Targeting single HDAC isoforms is considered to provide novel therapeutic options. HDAC6 is overexpressed in primary samples from patients with CTCL and preclinical studies using transgenic mice that spontaneously develop a CTCL-like disease, have suggested that combinations including HDAC6 inhibitors may be successful in the treatment of CTCL. PI3K inhibition is currently being tested in clinical trials for CTCL with promising results. Since HDAC6 is known to diminish the activity of Akt via its deacetylation, the aim of the present study was to evaluate the therapeutic potential of selective HDAC6 inhibitors in combination with PI3K inhibitors in CTCL. Through the genetic and pharmacological inhibition of HDAC6, it was demonstrated that combining HDAC6 with PI3K inhibition may be an attractive therapeutic option for patients with CTCL.