In vivo Imaging of Cutaneous T-Cell Lymphoma Migration to the Skin

Heterogeneity and plasticity of tissue-resident memory T cells in skin diseases and homeostasis: a review

Skin tissue-resident memory T (Trm) cells are produced by antigenic stimulation and remain in the skin for a long time without entering the peripheral circulation. In the healthy state Trm cells can play a patrolling and surveillance role, but in the disease state Trm cells differentiate into various phenotypes associated with different diseases, exhibit different localizations, and consequently have local protective or pathogenic roles, such as disease recurrence in vitiligo and maintenance of immune homeostasis in melanoma. The most common surface marker of Trm cells is CD69/CD103. However, the plasticity of tissue-resident memory T cells after colonization remains somewhat uncertain. This ambiguity is largely due to the variation in the functionality and ultimate destination of Trm cells produced from memory cells differentiated from diverse precursors. Notably, the presence of Trm cells is not stationary across numerous non-lymphoid tissues, most notably in the skin. These cells may reenter the blood and distant tissue sites during the recall response, revealing the recycling and migration potential of the Trm cell progeny. This review focuses on the origin and function of skin Trm cells, and provides new insights into the role of skin Trm cells in the treatment of autoimmune skin diseases, infectious skin diseases, and tumors.

Roles of CCR10/CCL27-CCL28 axis in tumour development: mechanisms, diagnostic and therapeutic approaches, and perspectives

Cancer is now one of the major causes of death across the globe. The imbalance of cytokine and chemokine secretion has been reported to be involved in cancer development. Meanwhile, CC chemokines have received considerable interest in cancer research. CCR10, as the latest identified CC chemokine receptor (CCR), has been implicated in the recruitment and infiltration of immune cells, especially lymphocytes, into epithelia such as skin via ligation to two ligands, CCL27 and CCL28. Other than homoeostatic function, several mechanisms have been shown to dysregulate CCR10/CCL27-CCL28 expression in the tumour microenvironment. As such, these receptors and ligands mediate T-cell trafficking in the tumour microenvironment. Depending on the types of lymphocytes recruited, CCR10/CCL27-CCL28 interaction has been shown to play conflicting roles in cancer development. If they were T helper and cytotoxic T cells and natural killer cells, the role of this axis would be tumour-suppressive. In contrast, if CCR10/CCL27-CCL28 recruited regulatory T cells, cancer-associated fibroblasts or myeloid-derived suppressor cells, it would lead to tumour progression. In addition to the trafficking of lymphocytes and immune cells, CCR10 also leads to the migration of tumour cells or endothelial cells (called angiogenesis and lymphangiogenesis) to promote tumour metastasis. Furthermore, CCR10 signalling triggers tumour-promoting signalling such as PI3K/AKT and mitogen-activated protein kinase/extracellular signal-regulated kinase, resulting in tumour cell growth. Since CCR10/CCL27-CCL28 is dysregulated in the tumour tissues, it is suggested that analysis and measurement of them might predict tumour development. Finally, it is hoped using therapeutic approaches based on this axis might increase our knowledge to overcome tumour progression.

Challenging Cutaneous T-Cell Lymphoma: What Animal Models Tell us So Far

Cutaneous T-cell lymphomas are characterized by heterogeneity of clinical variants, further complicated by genomic and microenvironmental variables. Furthermore, in vitro experiments are hampered by the low culture efficiency of these malignant cells. Animal models are essential for understanding the pathogenetic mechanisms underlying malignancy and for discovering new anticancer treatments. They are divided into two main categories: those in which tumors arise in the host owing to genetic modifications and those that use tumor cell transplantation. In this review, we summarize the attempts to decipher the complexity of the pathogenesis of cutaneous T-cell lymphoma by exploiting genetically modified and xenograft models.

CCL27 Signaling in the Tumor Microenvironment

Chemokines are a group of small proteins which play an important role in leukocyte migration and invasion. They are also involved in the cellular proliferation and migration of tumor cells.Chemokine CCL27 (cutaneous T cell-attracting chemokine, CTACK) is mainly expressed by keratinocytes of the normal epidermis. It is well known that this chemokine plays an important role in several inflammatory diseases of the skin, such as atopic dermatitis, contact dermatitis, and psoriasis. Moreover, several studies have shown an association between CCL27 expression and a variety of neoplasms including skin cancer.In this chapter, we address the role of chemokine CCL27 in the tumor microenvironment in the most relevant cancers of the skin and other anatomical locations. We also make a brief comment on future perspectives and the potential relation of CCL27 with different immunotherapeutic modalities.

Naïve/memory T-cell phenotypes in leukemic cutaneous T-cell lymphoma: Putative cell of origin overlaps disease classification

BACKGROUND

Mycosis fungoides (MF) and Sézary Syndrome (SS) are clinically distinct cutaneous T-cell lymphomas with strikingly similar morphologic and phenotypic features. Prior studies have suggested phenotypic differences based on markers of antigen experience, suggesting a different cell of origin.

METHODS

Seventy-nine involved peripheral blood or bone marrow samples from 33 patients with SS and 19 patients with MF were studied by 10-color flow cytometry, including CD62L, CD45RA, CCR4, and PD-1. Gated tumor events were classified as naïve (T_N ), central memory (T_CM ), effector memory (T_EM ), or effector memory with reacquired CD45RA (T_EMRA ); based on CD62L⁺ /CD45RA⁺ , CD62L⁺ /CD45RA^- , CD62L^- /CD45RA^- , or CD62L^- /CD45RA⁺ phenotype, respectively. Sequential specimens were compared to assess for phenotypic stability.

RESULTS

The naïve/memory phenotype of the neoplastic T-cells was markedly heterogeneous, with a dominant T_N , T_CM , T_EM , or T_EMRA subset on 11 (14%), 32 (41%), 30 (38%), and 6 (8%) cases, respectively. There was no correlation between the diagnosis of MF or SS and putative cell of origin (P = 0.4). Overexpression of CCR4 and PD1 was observed in most cases, with higher intensity in SS compared to MF. The naïve/memory phenotype remained the same for 10 patients up to 273 days after the initial analysis; while on six patients, the naïve/memory phenotype was different from the original phenotype.

CONCLUSIONS

Both SS and MF can have phenotypic features of any of the major naïve/memory T-cell subsets, which questions the current principle of "cell-of-origin" distinction between SS and MF. Phenotypic shifts within these subsets are common, suggesting a functional state rather than a cell-of-origin surrogate. © 2018 International Clinical Cytometry Society.

Cutaneous epitheliotropic T-cell lymphoma with systemic dissemination in a dog

Cutaneous epitheliotropic T-cell lymphoma (CETL) is characterized by neoplastic T-cell infiltration of the epidermis, adnexal structures, and oral mucosa. The objective of this report was to describe the pathological findings of a canine case of terminal-stage CETL. A 10-year-old, mixed-breed, neutered male dog was presented with erosion of the oral mucosa and mucocutaneous junction. The dog was diagnosed with CETL with no evidence of metastasis. Despite chemotherapy, the dog was re-presented with oral pain, vomiting, and diarrhea, and died 17 months after the first visit to the hospital. A complete autopsy was performed. Histologic examination of the primary lesion and systemic organs was performed. Gross examination revealed an advanced-stage oral lesion. Distinct tumor formation was not observed in the primary sites and systemic organs. Histologically, the primary oral lesion was characterized by massive intraepithelial infiltration of a large number of neoplastic lymphocytes. The neoplastic cells in the metastatic sites also showed exclusive epitheliotropic proliferation in organs, including the trachea, tonsils, esophagus, stomach, small intestine, colon, anal mucosa, liver, pancreas, kidneys, urinary bladder, prostate gland, ear canals, and auricular and ventral skin. Immunohistochemically, the neoplastic cells were positive for CD3 and negative for CD20 as well as CD79α, supporting a diagnosis of CETL with systemic dissemination. In canine CETL with systemic signs, systemic metastasis should be considered even without evident mass formation. Neoplastic lymphocytes of CETL showed distinct epitheliotropism even in the systemic metastatic sites.

High accuracy 4D cell tracking into explanted skin using two-photon excitation microscopy

Two-photon excitation microscopy (2PEM) analysis of large explanted organs is still laborious, principally because of tissue movements inducing lateral and axial drifts during extended imaging sessions. Here, we describe a two-step approach to track motile T cells in murine dorsal explanted skin with the best accuracy. First, we compared various explanted skin mounting methods for 2PEM analysis to define the setup allowing for minimal sample drift over time. Second, we developed two algorithms with the ImageJ software (National Institute of Health, Bethesda, MD) to correct the residual drift using lateral and axial registration of the collagen network. Finally, we applied the macro we developed to track fluorescent T cells in explanted skin. We found that our newly developed macro is more efficient than freely or commercially available software for shift correction, leading to more accurate velocity calculations. Our work provides a practical guide for investigators interested to employ skin-imaging approaches and offers a free alternative to commercial software for correcting lateral and axial drifts.

Application of Multiphoton Microscopy in Dermatological Studies: a Mini-Review

This review summarizes the historical and more recent developments of multiphoton microscopy, as applied to dermatology. Multiphoton microscopy offers several advantages over competing microscopy techniques: there is an inherent axial sectioning, penetration depths that compete well with confocal microscopy on account of the use of near-infrared light, and many two-photon contrast mechanisms, such as second-harmonic generation, have no analogue in one-photon microscopy. While the penetration depths of photons into tissue are typically limited on the order of hundreds of microns, this is of less concern in dermatology, as the skin is thin and readily accessible. As a result, multiphoton microscopy in dermatology has generated a great deal of interest, much of which is summarized here. The review covers the interaction of light and tissue, as well as the various considerations that must be made when designing an instrument. The state of multiphoton microscopy in imaging skin cancer and various other diseases is also discussed, along with the investigation of aging and regeneration phenomena, and finally, the use of multiphoton microscopy to analyze the transdermal transport of drugs, cosmetics and other agents is summarized. The review concludes with a look at potential future research directions, especially those that are necessary to push these techniques into widespread clinical acceptance.

Preclinical intravital microscopy of the tumour-stroma interface: invasion, metastasis, and therapy response

Key steps of cancer progression and therapy response depend upon interactions between cancer cells with the reactive tumour microenvironment. Intravital microscopy enables multi-modal and multi-scale monitoring of cancer progression as a dynamic step-wise process within anatomic and functional niches provided by the microenvironment. These niches deliver cell-derived and matrix-derived signals that enable cell subsets or single cancer cells to survive, migrate, grow, undergo dormancy, and escape immune surveillance. Beyond basic research, intravital microscopy has reached preclinical application to identify mechanisms of tumour-stroma interactions and outcome. We here summarise how n-dimensional 'dynamic histopathology' of tumours by intravital microscopy shapes mechanistic insight into cell-cell and cell-tissue interactions that underlie single-cell and collective cancer invasion, metastatic seeding at distant sites, immune evasion, and therapy responses.

Intravital imaging of a spheroid-based orthotopic model of melanoma in the mouse ear skin

Multiphoton microscopy is a powerful tool that enables the visualization of fluorescently tagged tumor cells and their stromal interactions within tissues in vivo. We have developed an orthotopic model of implanting multicellular melanoma tumor spheroids into the dermis of the mouse ear skin without the requirement for invasive surgery. Here, we demonstrate the utility of this approach to observe the primary tumor, single cell actin dynamics, and tumor-associated vasculature. These methods can be broadly applied to investigate an array of biological questions regarding tumor cell behavior in vivo.

Serum and tissue CTACK/CCL27 chemokine levels in early mycosis fungoides may be correlated with disease-free survival following treatment with interferon alfa and psoralen plus ultraviolet A therapy

BACKGROUND

Neoplastic T-cell recruitment into the skin is a critical step in the pathogenesis of mycosis fungoides (MF), and the cutaneous T-cell attracting chemokine, CTACK/CCL27, might be involved.

OBJECTIVES

To investigate the clinical and prognostic significance of CTACK/CCL27 levels in patients with early-stage MF.

METHODS

Serum samples and skin biopsy specimens were collected from 15 patients at the time of diagnosis and after the end of treatment with psoralen plus ultraviolet A/interferon alfa-2b combination therapy. Serum samples were also collected from 20 healthy donors as controls. CTACK/CCL27 serum levels were analysed by enzyme-linked immunosorbent assays. CTACK/CCL27 tissue expression was determined by immunohistochemistry on skin biopsy specimens taken at diagnosis and after therapy. Event-free survival was taken as the primary clinical outcome.

RESULTS

In patients with MF at diagnosis, CTACK/CCL27 serum levels were not significantly different from healthy controls, whereas CTACK/CCL27 expression in the skin was increased in 87% of cases compared with normal controls. After therapy, all patients obtained a clinical complete remission, serum levels did not change significantly and tissue expression remained abnormal in 80% of patients, even if complete histological remission was recorded. Serum levels were not significantly different in cases with different intensity of cutaneous immunostaining. Eight patients experienced a relapse: the combination of high CTACK/CCL27 levels both in sera and skin increased the probability of experiencing an event at 51 months from 36% to 83%.

CONCLUSIONS

Our data seem to indicate that CTACK/CCL27 levels in skin and sera after therapy might be correlated with risk of recurrence.

Intravital multiphoton imaging of immune responses in the mouse ear skin

Multiphoton (MP) microscopy enables the direct in vivo visualization, with high spatial and temporal resolution, of fluorescently tagged immune cells, extracellular matrix and vasculature in tissues. This approach, therefore, represents a powerful alternative to traditional methods of assessing immune cell function in the skin, which are mainly based on flow cytometry and histology. Here we provide a step-by-step protocol describing experimental procedures for intravital MP imaging of the mouse ear skin, which can be easily adapted to address many specific skin-related biological questions. We demonstrate the use of this procedure by characterizing the response of neutrophils during cutaneous inflammation, which can be used to perform in-depth analysis of neutrophil behavior in the context of the skin microanatomy, including the epidermis, dermis and blood vessels. Such experiments are typically completed within 1 d, but as the procedures are minimally invasive, it is possible to perform longitudinal studies through repeated imaging.

Selectins and Associated Adhesion Proteins in Inflammatory disorders

Inflammation is defined as the normal response of living tissue to injury or infection. It is important to emphasize two components of this definition. First, that inflammation is a normal response and, as such, is expected to occur when tissue is damaged. Infact, if injured tissue does not exhibit signs of inflammation this would be considered abnormal and wounds and infections would never heal without inflammation. Secondly, inflammation occurs in living tissue, hence there is need for an adequate blood supply to the tissues in order to exhibit an inflammatory response. The inflammatory response may be triggered by mechanical injury, chemical toxins, and invasion by microorganisms, and hypersensitivity reactions. Three major events occur during the inflammatory response: the blood supply to the affected area is increased substantially, capillary permeability is increased, and leucocytes migrate from the capillary vessels into the surrounding interstitial spaces to the site of inflammation or injury. The inflammatory response represents a complex biological and biochemical process involving cells of the immune system and a plethora of biological mediators. Cell-to-cell communication molecules such as cytokines play an extremely important role in mediating the process of inflammation. Inflammation and platelet activation are critical phenomena in the setting of acute coronary syndromes. An extensive exposition of this complex phenomenon is beyond the scope of this article (Rankin 2004).

Thymus and activation-regulated chemokine in different stages of mycosis fungoides: tissue and serum levels

BACKGROUND/OBJECTIVES

Thymus and activation-regulated chemokine (CCL17) is a member of the CC chemokines known to attract T-helper 2 type memory T cells and to participate in different T-helper 2 diseases. The aim of this study is to determine both serum and tissue levels of thymus and activation-regulated chemokine in patients with different stages of mycosis fungoides.

METHODS

Thirty-two patients with different stages of mycosis fungoides and 10 controls were included in the study. Skin biopsies and blood samples were taken to evaluate both tissue and serum levels of thymus and activation-regulated chemokine using the enzyme-linked immunosorbent assay method.

RESULTS

The mean tissue level of thymus and activation-regulated chemokine in 10 tumour-stage patients was significantly higher (P = 0.002) than in the controls. The mean serum level of thymus and activation-regulated chemokine in all stages of mycosis fungoides patients was not significantly elevated (P = 0.131, 0.725 and 0.622) compared with controls. Both tissue and serum levels of thymus and activation-regulated chemokine correlated significantly with both the disease extent and duration in the three different stages of mycosis fungoides.

CONCLUSION

Thymus and activation-regulated chemokine may be a marker for disease activity of mycosis fungoides, and may have a role in monitoring disease progression.