Transimmunization for cutaneous T cell lymphoma: A phase I study

Take a spin: Apheresis in the care of adult leukaemia patients

Apheresis is an automated process to separate the whole blood of a patient or a donor, collect or remove specific blood components, and return the remaining back to the individual. Apheresis is an integral part of blood and marrow transplantation and has been increasingly utilized in novel cellular therapies for a variety of blood disorders. This review uses clinical cases to highlight the multiple roles of apheresis in the care of adult leukaemia patients, including therapeutic leukapheresis in hyperleukocytosis, mobilized peripheral blood hematopoietic progenitor cell collection in donors, mononucleated cell collection in preparation of donor lymphocyte infusion or chimeric antigen receptor T cells manufacture, and extracorporeal photopheresis in the treatment of graft versus host diseases.

European dermatology forum - updated guidelines on the use of extracorporeal photopheresis 2020 - part 1

Background

Following the first investigational study on the use of extracorporeal photopheresis for the treatment of cutaneous T‐cell lymphoma published in 1983, this technology has received continued use and further recognition for additional earlier as well as refractory forms. After the publication of the first guidelines for this technology in the JEADV in 2014, this technology has maintained additional promise in the treatment of other severe and refractory conditions in a multi‐disciplinary setting. It has confirmed recognition in well‐known documented conditions such as graft‐versus‐host disease after allogeneic bone marrow transplantation, systemic sclerosis, solid organ transplant rejection including lung, heart and liver and to a lesser extent inflammatory bowel disease.

Materials and methods

In order to further provide recognized expert practical guidelines for the use of this technology for all indications, the European Dermatology Forum (EDF) again proceeded to address these questions in the hands of the recognized experts within and outside the field of dermatology. This was done using the recognized and approved guidelines of EDF for this task. All authors had the opportunity to review each contribution as it was added.

Results and conclusion

These updated 2020 guidelines provide at present the most comprehensive available expert recommendations for the use of extracorporeal photopheresis based on the available published literature and expert consensus opinion. The guidelines are divided in two parts: PART I covers cutaneous T‐cell lymphoma, chronic graft‐versus‐host disease and acute graft‐versus‐host disease while PART II will cover scleroderma, solid organ transplantation, Crohn's disease, use of ECP in paediatrics practice, atopic dermatitis, type 1 diabetes, pemphigus, epidermolysis bullosa acquisita and erosive oral lichen planus.

Transimmunization restores immune surveillance and prevents recurrence in a syngeneic mouse model of ovarian cancer

Ovarian cancer accounts for most deaths from gynecologic malignancies. Although more than 80% of patients respond to first-line standard of care, most of these responders present with recurrence and eventually succumb to carcinomatosis and chemotherapy-resistant disease. To improve patient survival, new modalities must, therefore, target or prevent recurrent disease. Here we describe for the first time a novel syngeneic mouse model of recurrent high-grade serous ovarian cancer (HGSOC), which allows immunotherapeutic interventions in a time course relevant to human carcinomatosis and disease course. Using this model, we demonstrate the efficacy of Transimmunization (TI), a dendritic cell (DC) vaccination strategy that uses autologous and physiologically derived DC loaded with autologous whole tumor antigens. TI has been proven successful in the treatment of human cutaneous T cell lymphoma and we report for the first time its in vivo efficacy against an intra-peritoneal solid tumor. Given as a single therapy, TI is able to elicit an effective anti-tumor immune response and inhibit immune-suppressive crosstalks with sufficient power to curtail tumor progression and establishment of carcinomatosis and recurrent disease. Specifically, TI is able to inhibit the expansion of tumor-associated macrophages as well as myeloid-derived suppressive cells consequently restoring T cell immune-surveillance. These results demonstrate the possible value of TI in the management of ovarian cancer and other intra-peritoneal tumors.

Extracorporeal photochemotherapy induces bona fide immunogenic cell death

Extracorporeal photochemotherapy (ECP) is employed for the management of cutaneous T cell lymphoma (CTCL). ECP involves the extracorporeal exposure of white blood cells (WBCs) to a photosensitizer, 8-methoxypsoralen (8-MOP), in the context of ultraviolet A (UVA) radiation, followed by WBC reinfusion. Historically, the therapeutic activity of ECP has been attributed to selective cytotoxicity on circulating CTCL cells. However, only a fraction of WBCs is exposed to ECP, and 8-MOP is inactive in the absence of UVA light, implying that other mechanisms underlie the anticancer effects of ECP. Recently, ECP has been shown to enable the physiological differentiation of monocytes into dendritic cells (DCs) that efficiently cross-present tumor-associated antigens (TAAs) to CD8⁺ T lymphocytes to initiate cognate immunity. However, the source of TAAs and immunostimulatory signals for such DCs remains to be elucidated. Here, we demonstrate that 8-MOP plus UVA light reduces melanoma cell viability along with the emission of ICD-associated danger signals including calreticulin (CALR) exposure on the cell surface and secretion of ATP, high mobility group box 1 (HMGB1) and type I interferon (IFN). Consistently, melanoma cells succumbing to 8-MOP plus UVA irradiation are efficiently engulfed by monocytes, ultimately leading to cross-priming of CD8⁺ T cells against cancer. Moreover, malignant cells killed by 8-MOP plus UVA irradiation in vitro vaccinate syngeneic immunocompetent mice against living cancer cells of the same type, and such a protection is lost when cancer cells are depleted of calreticulin or HMGB1, as well as in the presence of an ATP-degrading enzyme or antibodies blocking type I IFN receptors. ECP induces bona fide ICD, hence simultaneously providing monocytes with abundant amounts of TAAs and immunostimulatory signals that are sufficient to initiate cognate anticancer immunity.

Extracorporeal Photopheresis-An Overview

Extracorporeal photopheresis (ECP) has been in clinical use for over three decades after receiving FDA approval for the palliative treatment of the Sézary Syndrome variant of cutaneous T-cell lymphoma (CTCL) in 1988. After the first positive experiences with CTCL, additional indications have been successfully explored including areas such as graft-vs.-host disease (GVHD), scleroderma, and solid organ transplantation. The mechanism of action is still not fully resolved, but important steps in understanding ECP in recent years have been very informative. Originally, the primary hypothesis stated that psoralen and ultraviolet A (UVA) in combination induce apoptosis in the treated immune cells. This view shifted in favor of dendritic cell initiation, modification of the cytokine profile and stimulation of several T-cell lineages, in particular regulatory T-cells. A number of ECP guidelines have been produced to optimize treatment regimens in the clinical context. In CTCL, enough evidence is available for the use of ECP as a first line treatment for Sézary Syndrome (SS), but also as a second line or rescue treatment in therapy-refractory forms of mycosis fungoides (MF). ECP in the treatment of acute and chronic GVHD has shown promising results as second line therapy in steroid-refractory presentations. In solid organ transplantation, ECP has been used to increase tissue tolerance and decrease infections with opportunistic pathogens, attributed to the use of high doses of immunosuppressive medication. Infection with cytomegalovirus (CMV) remains a limiting factor affecting survival in solid organ transplantation and the role of ECP will be discussed in this review. A trend toward prophylactic use of ECP can be observed and may further contribute to improve the outcome in many patients. To further deepen our knowledge of ECP and thus facilitate its use in patients that potentially benefit most from it, future prospective randomized trials are urgently needed in this rapidly growing field. The aim of this review is to (1) introduce the method, (2) give an overview where ECP has shown promising effects and has become an essential part of treatment protocols, and (3) to give recommendations on how to proceed in numerous indications.

Extracorporeal Photochemotherapy Drives Monocyte-to-Dendritic Cell Maturation to Induce Anticancer Immunity

Extracorporeal photochemotherapy (ECP) is a cancer immunotherapy for cutaneous T-cell lymphoma (CTCL) operative in more than 350 centers worldwide. Although its efficacy and favorable safety profile have driven its widespread use, elucidation of its underlying mechanism has been difficult. In this study, we identify the principal contributors to the anticancer immunotherapeutic effects of ECP, with the goal of enhancing potency and broadening applicability to additional malignancies. First, we scaled down the clinical ECP leukocyte-processing device to mouse size. Second, we used that miniaturized device to produce a cellular vaccine that regularly initiated therapeutic antimelanoma immunity. Third, we individually subtracted key factors from either the immunizing inoculum or the treated animal to ascertain their contribution to the in vivo antimelanoma response. Platelet-signaled monocyte-to-dendritic cell (DC) differentiation followed by sorting/processing/presentation of tumor antigens derived from internalized apoptotic tumor cells were absolute requirements. As in clinical ECP, immunogenic cell death of tumor cells was finely titrated by DNA cross-linkage mediated by photoactivated 8-methoxypsoralen (8-MOPA). ECP-induced tumor-loaded DC were effective immunotherapeutic agents only if they were spared exposure to 8-MOPA, indicating that healthy DC are required for ECP. Infusion of responder T cells into naïve tumor-challenged mice established the protective role of stimulated T-cell antitumor immunity. Collectively, these results reveal that selective antitumor effects of ECP are initiated by tumor antigen-loaded, ECP-induced DC, which promote potent collaboration between CD4 and CD8 tumor-specific T cells. These mechanistic insights suggest potential therapeutic applicability of ECP to solid tumors in addition to CTCL.Significance: These findings identify principal cellular contributors to the anticancer immunotherapeutic impact of ECP and suggest this treatment may be applicable to a broad spectrum of immunogenic malignancies. Cancer Res; 78(14); 4045-58. ©2018 AACR.

Cutaneous T-cell lymphoma: 2017 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multi-disciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with biologic-response modifiers or histone deacetylase inhibitors prior to escalating therapy to include systemic, single-agent chemotherapy. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

X-Ray Psoralen Activated Cancer Therapy (X-PACT)

This work investigates X-PACT (X-ray Psoralen Activated Cancer Therapy): a new approach for the treatment of solid cancer. X-PACT utilizes psoralen, a potent anti-cancer therapeutic with current application to proliferative disease and extracorporeal photopheresis (ECP) of cutaneous T Cell Lymphoma. An immunogenic role for light-activated psoralen has been reported, contributing to long-term clinical responses. Psoralen therapies have to-date been limited to superficial or extracorporeal scenarios due to the requirement for psoralen activation by UVA light, which has limited penetration in tissue. X-PACT solves this challenge by activating psoralen with UV light emitted from novel non-tethered phosphors (co-incubated with psoralen) that absorb x-rays and re-radiate (phosphoresce) at UV wavelengths. The efficacy of X-PACT was evaluated in both in-vitro and in-vivo settings. In-vitro studies utilized breast (4T1), glioma (CT2A) and sarcoma (KP-B) cell lines. Cells were exposed to X-PACT treatments where the concentrations of drug (psoralen and phosphor) and radiation parameters (energy, dose, and dose rate) were varied. Efficacy was evaluated primarily using flow cell cytometry in combination with complimentary assays, and the in-vivo mouse study. In an in-vitro study, we show that X-PACT induces significant tumor cell apoptosis and cytotoxicity, unlike psoralen or phosphor alone (p<0.0001). We also show that apoptosis increases as doses of phosphor, psoralen, or radiation increase. Finally, in an in-vivo pilot study of BALBc mice with syngeneic 4T1 tumors, we show that the rate of tumor growth is slower with X-PACT than with saline or AMT + X-ray (p<0.0001). Overall these studies demonstrate a potential therapeutic effect for X-PACT, and provide a foundation and rationale for future studies. In summary, X-PACT represents a novel treatment approach in which well-tolerated low doses of x-ray radiation are delivered to a specific tumor site to generate UVA light which in-turn unleashes both short- and potentially long-term antitumor activity of photo-active therapeutics like psoralen.

Selective photodepletion of malignant T cells in extracorporeal photopheresis with selenorhodamine photosensitizers

Extracorporeal photopheresis (ECP) has been used successfully in the treatment of erythrodermic cutaneous T cell lymphoma (CTCL), and other T cell-mediated disorders. Not all patients obtain a significant or durable response from ECP. The design of a selective photosensitizer that spares desirable lymphocytes while targeting malignant T cells may promote cytotoxic T cell responses and improve outcomes after ECP. A series of selenorhodamines built with variations of the Texas red core targeted the mitochondria of malignant T cells, were phototoxic to malignant T cells presumably via their ability to generate singlet oxygen, and were transported by P-glycoprotein (P-gp). To determine the selectivity of the photosensitizers in the ECP milieu, staphylococcal enterotoxin B (SEB)-stimulated and non-stimulated human lymphocytes were combined with HUT-78 cells (a CTCL) to simulate ECP. The amide-containing analogues of the selenorhodamines were transported more rapidly than the thioamide analogues in monolayers of MDCKII-MDR1 cells and, consequently, were extruded more rapidly from P-gp-expressing T cells than the corresponding thioamide analogues. Selenorhodamine 6 with the Texas red core and a piperidylamide functionality was phototoxic to >90% of malignant T cells while sparing >60% of both stimulated and non-stimulated T cells. In the resting T cells, (63±7)% of the CD4+ T cell compartment, and (78±2.5)% of the CD8+ cytotoxic T cell population were preserved, resulting in an enrichment of healthy and cytotoxic T cells after photodepletion.

Cutaneous T-cell lymphoma: 2016 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral, or blood involvement are generally approached with biologic-response modifiers or histone deacetylase inhibitors before escalating therapy to include systemic, single-agent chemotherapy. In highly-selected patients, allogeneic stem-cell transplantation may be considered, as this may be curative in some patients.

Extracorporeal photopheresis after heart transplantation

The addition of extracorporeal photopheresis (ECP) to a standard immunosuppressive drug therapy after heart transplantation in clinical studies has shown to be beneficial, for example, by reducing acute rejection, allograft vasculopathy or CMV infection. However, the protocols varied considerably, have a predetermined finite number of ECP treatments and adjuvant immunosuppressive regimens used in combination with ECP have differed significantly. Furthermore, there are scarce data to guide which patients should be treated with ECP and when or who would benefit further if ECP were to be continued long term to increase the safety by reducing immunosuppressive drug toxicities without losing efficacy. The knowledge of the tolerance-inducing effects of ECP-like upregulation of regulatory T cells and of dendritic cells may allow to develop a strategy to monitor immunomodulation effects of ECP to further identify ECP responders, the optimal individual ECP schedule and whether ECP therapy can replace or reduce immunosuppressive drug therapy.

National Institutes of Health State of the Science Symposium in Therapeutic Apheresis: scientific opportunities in extracorporeal photopheresis

The clinical use of extracorporeal photopheresis (ECP) for accepted indications such as graft-versus-host disease, transplant rejection, and cutaneous T-cell lymphoma continues to increase. Expanded applications for ECP, such as the treatment of select autoimmune diseases, are being explored. Extracorporeal photopheresis's capacity to both immunotolerize in the autoreactive setting, while immunizing against a lymphoma is unusual and suggestive of a unique mechanism. It is likely that ECP's induction of dendritic cells is key to its efficacy in both of these settings, but exactly how ECP impacts other immune components and their interactions is not fully understood. Further basic science research is necessary to elucidate how these dissimilar cellular activities are functionally integrated. On the clinical side, collaborative multicenter trials designed to recognize the principal variables controlling therapeutic responses and improve prognostic indicators may enable tailoring devices, treatment schedules, and doses to the needs of the individual patients or diseases. This review describes our current understanding of how ECP influences the immune system, reviews the existing clinical applications of ECP, and explores areas for future basic science and clinical research as presented at the National Institutes of Health State of the Science Symposium in Therapeutic Apheresis in November 2012.

Guidelines on the use of extracorporeal photopheresis

BACKGROUND

After the first investigational study on the use of extracorporeal photopheresis for the treatment of cutaneous T-cell lymphoma was published in 1983 with its subsequent recognition by the FDA for its refractory forms, the technology has shown significant promise in the treatment of other severe and refractory conditions in a multi-disciplinary setting. Among the major studied conditions are graft versus host disease after allogeneic bone marrow transplantation, systemic sclerosis, solid organ transplant rejection and inflammatory bowel disease.

MATERIALS AND METHODS

In order to provide recognized expert practical guidelines for the use of this technology for all indications the European Dermatology Forum (EDF) proceeded to address these questions in the hands of the recognized experts within and outside the field of dermatology. This was done using the recognized and approved guidelines of EDF for this task.

RESULTS AND CONCLUSION

These guidelines provide at present the most comprehensive available expert recommendations for the use of extracorporeal photopheresis based on the available published literature and expert consensus opinion.

Cutaneous T-cell lymphoma: 2014 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis Fungoides (MF) or Sézary Syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

TNMB (tumor, node, metastasis, and blood) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral or blood involvement are generally approached with biologic-response modifiers or histone deacetylase inhibitors prior to escalating therapy to include systemic, single-agent chemotherapy. Multiagent chemotherapy (e.g., CHOP) may be employed for those patients with extensive visceral involvement requiring rapid disease control. In highly selected patients, allogeneic stem-cell transplantation may be considered.

Integrin-driven monocyte to dendritic cell conversion in modified extracorporeal photochemotherapy

Due to clinical efficacy and safety profile, extracorporeal photochemotherapy (ECP) is a commonly used cell treatment for patients with cutaneous T cell lymphoma (CTCL) and graft-versus-host disease (GVHD). The capacity of ECP to induce dendritic antigen-presenting cell (DC)-mediated selective immunization or immunosuppression suggests a novel mechanism involving pivotal cell signalling processes that have yet to be clearly identified as related to this procedure. In this study we employ two model systems of ECP to dissect the role of integrin signalling and adsorbed plasma proteins in monocyte-to-DC differentiation. We demonstrate that monocytes that were passed through protein-modified ECP plates adhered transiently to plasma proteins, including fibronectin, adsorbed to the plastic ECP plate and activated signalling pathways that initiate monocyte-to-DC conversion. Plasma protein adsorption facilitated 54·2 ± 4·7% differentiation, while fibronectin supported 29·8 ± 7·2% differentiation, as detected by DC phenotypic expression of membrane CD80 and CD86, as well as CD36, human leucocyte antigen D-related (HLA-DR) and cytoplasmic CD83. Further, we demonstrate the ability of fibronectin and other plasma proteins to act through cell adhesion via the ubiquitous arginine-glycine-aspartic (RGD) motif to drive monocyte-to-DC differentiation, with high-density RGD substrates supporting 54·1 ± 5·8% differentiation via αVβ3 and α5β1integrin signalling. Our results demonstrate that plasma protein binding integrins and plasma proteins operate through specific binding domains to induce monocyte-to-DC differentiation in ECP, providing a mechanism that can be harnessed to enhance ECP efficacy.

Induction of monocyte-to-dendritic cell maturation by extracorporeal photochemotherapy: initiation via direct platelet signaling

Extracorporeal Photochemotherapy (ECP) is a widely used therapy for cutaneous T cell lymphoma (CTCL). Although the mechanism of clinical action of ECP is not precisely established, previous studies have shown evidence of induction of dendritic cells (DCs). Here we show that, under flow conditions similar to those in post-capillary venules, ECP promotes platelet immobilization and activation, initiating stepwise receptor-ligand interactions with monocytes, which then differentiate into DC. These findings clarify how ECP directly stimulates DC maturation; suggest a new clinically applicable approach to the obtainment of DC; and identify a novel mechanism that may reflect physiological induction of DC.

Mechanistic insights into extracorporeal photochemotherapy: efficient induction of monocyte-to-dendritic cell maturation

Extracorporeal photochemotherapy (ECP) is a widely used immunotherapy for cutaneous T cell lymphoma, as well as immunomodulation of graft-versus-host disease (GVHD) and transplanted organ rejection. ECP's mechanism encompasses large-scale physiologic platelet induction of dendritic cells (DCs). The normal bidirectional immunologic talents of DCs likely contribute heavily to ECP's capacity to immunize against tumor antigens, while also suppressing transplant immunopathology. Our understanding of how ECP physiologically induces monocyte-to-DC maturation can enhance the treatment's potency, potentially broaden its use to other cancers and autoimmune disorders and tailor its application to individual patients' diseases. ECP's next decade is filled with promise.

Cutaneous T-cell lymphoma: 2011 update on diagnosis, risk-stratification, and management

DISEASE OVERVIEW

Cutaneous T-cell lymphomas are a heterogenous group of T-cell lymphoproliferative disorders involving the skin, the majority of which may be classified as Mycosis fungoides (MF) or Sézary syndrome (SS).

DIAGNOSIS

The diagnosis of MF or SS requires the integration of clinical and histopathologic data.

RISK-ADAPTED THERAPY

Tumor, node, metastasis, and blood (TNMB) staging remains the most important prognostic factor in MF/SS and forms the basis for a "risk-adapted," multidisciplinary approach to treatment. For patients with disease limited to the skin, expectant management or skin-directed therapies is preferred, as both disease-specific and overall survival for these patients is favorable. In contrast, patients with advanced-stage disease with significant nodal, visceral, or blood involvement are generally approached with biologic-response modifiers, denileukin diftitox, and histone deacetylase inhibitors before escalating therapy to include systemic, single-agent chemotherapy. Multiagent chemotherapy may be used for those patients with extensive visceral involvement requiring rapid disease control. In highly-selected patients with disease refractory to standard treatments, allogeneic stem-cell transplantation may be considered.

In situ vaccination against mycosis fungoides by intratumoral injection of a TLR9 agonist combined with radiation: a phase 1/2 study

We have developed and previously reported on a therapeutic vaccination strategy for indolent B-cell lymphoma that combines local radiation to enhance tumor immunogenicity with the injection into the tumor of a TLR9 agonist. As a result, antitumor CD8(+) T cells are induced, and systemic tumor regression was documented. Because the vaccination occurs in situ, there is no need to manufacture a vaccine product. We have now explored this strategy in a second disease: mycosis fungoides (MF). We treated 15 patients. Clinical responses were assessed at the distant, untreated sites as a measure of systemic antitumor activity. Five clinically meaningful responses were observed. The procedure was well tolerated and adverse effects consisted mostly of mild and transient injection site or flu-like symptoms. The immunized sites showed a significant reduction of CD25(+), Foxp3(+) T cells that could be either MF cells or tissue regulatory T cells and a similar reduction in S100(+), CD1a(+) dendritic cells. There was a trend toward greater reduction of CD25(+) T cells and skin dendritic cells in clinical responders versus nonresponders. Our in situ vaccination strategy is feasible also in MF and the clinical responses that occurred in a subset of patients warrant further study with modifications to augment these therapeutic effects. This study is registered at www.clinicaltrials.gov as NCT00226993.

The Combination of Immunosuppressive Drugs with 8-Methoxypsoralen and Ultraviolet a Light Modulates the Myeloid-Derived Dendritic Cell Function

The functional properties of myeloid dendritic cells (DCs) differ, depending on microenvironmental factors as well as on their stage of maturation. The main approaches for the selective enhancement of the tolerogenic properties of DCs include the induction of a pharmacological arrest of the DCs maturation and the genetical engineering of DCs expressing immunosuppressive molecules. Several immunosuppressive/anti-inflammatory agents have been discovered that potentially inhibit DC maturation and immunogenicity. Photopheresis (ECP) is an immunomodulatory therapy in which leucocytes are exposed to 8-methoxypsoralen (8-MOP) and ultraviolet (UV) A radiation (PUVA). The combination of ECP with immunosuppressive agents has demonstrated efficacy in the management of transplanted patients by reducing either the incidence of organ rejection or the pharmacological toxicity. In particular, we have observed in hepatitis C virus (HCV)-positive patients that the same combination has reduced the immunosuppressive burden and improved sustainability and efficacy of pre-emptive antiviral therapy after liver transplantation. Therefore, in our work we investigated the in vitro effects of PUVA, combined with immunosuppressive drugs (IDs), on both in vitro human DC generation and maturation, in order to contribute to understanding the immunological mechanisms underlying this pharmacological combination. Monocyte PUVA-treatment was performed by using an in vitro experimental protocol that we previously described. PUVA-treated or -untreated highly purified CD14+ cells were incubated with the association of the immunosuppressive drugs, used in the management of liver transplantation, at two different concentrations, in the presence of IL-4 and GM-CSF. The treatment with IDs at the highest concentration (corresponding to that used in clinical practice), alone or in association with PUVA, induced an immunosuppressive effect, by impairing both DC generation and maturation. Neither immunosuppressive drugs at the lowest concentration nor their combination with PUVA affected myeloid DC generation, but modified DC functions, strengthening the induction of a tolerogenic pattern. As this ID concentration was arbitrarily chosen, further experiments could highlight whether lower concentrations than those used in clinical practice would elicit the same effect on DCs and potentially improve their functional properties. This work describes an original experimental approach exploring the in vitro mechanism of action of the combined procedure of PUVA with immunosuppressive drugs, used in liver transplantation, on DCs generation and function. Our results contribute to the knowledge of the mechanisms of action of this combined procedure on DCs, suggesting useful therapeutic implications for the in vivo therapy.

Rapid generation of maturationally synchronized human dendritic cells: contribution to the clinical efficacy of extracorporeal photochemotherapy

Extracorporeal photochemotherapy (ECP) is widely used to treat cutaneous T-cell lymphoma, graft-versus-host disease, and allografted organ rejection. Its clinical and experimental efficacy in cancer immunotherapy and autoreactive disorders suggests a novel mechanism. This study reveals that ECP induces a high percentage of processed monocytes to enter the antigen-presenting dendritic cell (DC) differentiation pathway, within a single day, without added cytokines, as determined by enhanced expression of relevant genes. The resulting DCs are capable of processing and presentation of exogenous and endogenous antigen and are largely maturationally synchronized, as assessed by the level of expression of costimulatory surface molecules. Principal component analysis of the ECP-induced monocyte transcriptome reveals that activation or suppression of more than 1100 genes produces a reproducible distinctive molecular signature, common to ECP-processed monocytes from normal subjects, and those from patients. Because ECP induces normal monocytes to enter the DC differentiation pathway, this phenomenon is independent of disease state. The efficiency with which ECP stimulates new functional DCs supports the possibility that these cells participate prominently in the clinical successes of the treatment. Appropriately modified by future advances, ECP may potentially offer a general source of therapeutic DCs.

In vitro experiments demonstrate that monocytes and dendritic cells are rendered apoptotic by extracorporeal photochemotherapy, but exhibit unaffected surviving and maturing capacity after 30 Gy gamma irradiation

Extracorporeal photochemotherapy (ECP) has been shown to induce apoptosis in lymphocytes. Until recently the prevailing opinion has been that the monocytes were mainly not affected by this treatment. This study has investigated the effect of ECP and gamma irradiation on monocytes and immature dendritic cells (DC) in vitro and followed the ability of the cells to differentiate and survive post treatment. ECP induced apoptosis in lymphocytes, monocytes and immature DC within 72 h following treatment, in contrast to 30 Gy gamma irradiation, which seemed mainly to affect lymphocytes. The minority of the surviving ECP-treated monocytes presented a reduced ability to differentiate into immature DC within this time frame. We also demonstrated that immature DC after ECP-treatment lost their normal ability to mature on stimulation with lipopolysaccharide. As monocytes and immature DC seem to have a reduced ability to differentiate after ECP-treatment, it is suggested that the therapeutic effect of ECP is caused by in vivo effects of reinfused apoptotic cells, rather than by infusion of monocytes induced to differentiate into immature DC.

Extracorporeal photopheresis: Lighting the way to immunomodulation

Photopheresis, initially established as an effective treatment of cutaneous T-cell lymphoma, has in recent years also been used to treat chronic graft vs. host disease, heart transplant rejection, and several other conditions requiring immunosuppression. Despite reported beneficial results of this procedure in treatment of various conditions, randomized controlled clinical trials are lacking for the majority of suggested indications. Furthermore, the mechanisms of action of this procedure are still unclear. Deeper understanding of the molecular basis of photopheresis-based immunomodulation will allow better selection of patients to be treated and will facilitate development of novel, minimally toxic immunomodulatory treatments.

Extracorporeal photopheresis reverses experimental graft-versus-host disease through regulatory T cells

Extracorporeal photopheresis (ECP), a technique that exposes isolated white blood cells to photoactivatable 8-methoxypsoralen and ultraviolet A radiation, is used clinically to treat cutaneous T-cell lymphoma and immune-mediated diseases such as graft-versus-host disease (GVHD). ECP is thought to control these diseases in part through direct induction of lymphocyte apoptosis, but its effects on the immune system beyond apoptosis remain poorly characterized. We have developed a novel method for incorporating ECP treatment into well-established and clinically relevant murine models of GVHD to examine its effects during an ongoing immune response. We demonstrate that the transfer of cells treated with ECP reverses established GVHD by increasing donor regulatory T cells and indirectly reducing the number of donor effector lymphocytes that themselves had never been exposed to psoralen and ultraviolet A radiation.

Development of immunogenic tumor-loaded dendritic cells through physical perturbation and apoptotic cell loading

To improve understanding of the forces that drive monocytes to transition into dendritic cells (Liyanage et al., 2002), we developed an experimental system that converts monocytes to DC by passage of leukocytes through a 400 microm silica bead column. The results demonstrate that overnight culture of column-treated monocytes causes a phenotypic conversion that is characteristically displayed by immature DC. These phenotypic changes were enhanced when the DC were loaded with apoptotic cells, leading to increased expression of the DC maturation-associated markers CD83, CD80 and the chemokine receptor CCR7. The DC demonstrated potent induction of allogeneic T cell proliferation and the capacity to activate autologous CD8(+) T cells. The CD8 T cells expressed augmented levels of perforin, IFN-gamma and TNF-alpha and mediated CTCL cell apoptosis. These studies demonstrate that physical contact with silica beads combined with loading of apoptotic tumor cells induces synchronized, rapid conversion of human monocytes to DC, which can efficiently stimulate CD8(+) T cells. These results may aid in the development of more efficient DC vaccines that can be loaded with the universe of antigens available in apoptotic tumor cells in a rapid, clinically practical fashion.

Extracorporeal Photochemotherapy as a Challenging Treatment for Cutaneous T-Cell Lymphoma, Acute and Chronic Graft-versus-Host Disease, Organ Rejection and T-Lymphocyte-Mediated Autoimmune Diseases

SUMMARY: 20 years ago, in 1987, Edelson and co-workers published their first report on the effectiveness of a new procedure, called extracorporeal photochemotherapy (ECP), in patients with advanced stage cutaneous T-cell lymphoma (CTCL). The positive response (>70% overall) achieved in those patients encouraged several groups to try out this new technology in other T-lymphocyte-mediated autoimmune diseases and a number of dermatological diseases, which sometimes gave conflicting results. In the following years, ECP obtained FDA approval as first line treatment in CTCL. In the 1990s ECP was applied to acute and chronic graft-versus-host disease (GvHD) refractory to conventional immunosuppressive therapy and proved to be effective in >60% of cases of this larger patient population. Today, although the effectiveness of ECP in GvHD is generally acknowledged, this is mainly based on retrospective or observational studies, as data from large, randomized multicenter trials, has yet to be published. Moreover, ECP's real mechanism of action and optimal treatment schedule are still under investigation. The aim of this review is to summarize knowledge acquired to date about ECP.

Clinical-scale generation of strongly CD83-expressing dendritic cells using extracorporeal photopheresis

BACKGROUND

Many strategies are currently being pursued in order to generate mature dendritic cells (DC) to be used for immunotherapy. A potent anti-tumour influence by extracorporeal photopheresis has been documented for cutaneous T-cell lymphoma, and a major mechanism of action has been suggested to be generation of DC presenting tumour antigens.

PURPOSE

To determine the potential of a simple clinical photopheresis protocol for large-scale development of mature DC.

METHODS

A standard monocyte-enriched leukapheresis preparation of 10(9)-10(10) cells was derived during each of five consecutive treatment sessions of a patient with cutaneous T-cell lymphoma. The cells were incubated overnight in autologous plasma with no addition of growth medium. Cell surface lymphocyte, monocyte and DC markers were determined using multi-colour flow cytometry.

RESULTS

We find signs of activation of the CD14+ monocytes, as well as the appearance of a minor population of mature DC negative for CD14 but with strong CD83 expression.

CONCLUSIONS

With a procedure appropriate for routine clinical use, a total number of 10(6)-10(7) DC ready for patient reinfusion can be prepared within 24 h. Our findings indicate the need to further explore the capacity of photopheresis to stimulate cancer patients' anti-tumour defence reaction.

In vitro treatment of monocytes with 8-methoxypsolaren and ultraviolet A light induces dendritic cells with a tolerogenic phenotype

Extracorporeal photopheresis (ECP) has been considered an efficient dendritic cell (DC) therapy, used for treating both T cell malignancy, as well as T cell-mediated diseases. During the ECP procedure leucocytes are exposed to photoactivable agent 8-methoxypsolaren (8-MOP) and ultraviolet (UV) A radiation (PUVA) prior to reinfusion. Despite its clinical efficacy the mechanism of action remains elusive. As it has been reported that ECP might promote the differentiation of monocytes into immature DCs, we investigated the effects of UVA light (2 J/cm(2)) and 8-MOP (100 ng/ml) on in vitro monocyte-to-DC differentiation from normal donors. DCs were generated from human purified CD14(+) cells. Because monocytes are killed by PUVA and taking into account that only 5-10% of circulating mononuclear cells are exposed to PUVA during the ECP procedure, we developed an assay in which 10% of PUVA-treated monocytes were co-cultured with untreated monocytes. We first demonstrate that the presence of 10% apoptotic cells and monocyte activation were not enough to induce monocyte differentiation into DCs. Adding cytokines to our culture system, we obtained immature DCs characterized by significantly higher phagocytic activity and human leucocyte antigen D-related (HLA-DR) expression. These DCs preserved the capacity to be activated by lipopolysaccharide, but showed a reduced capacity to induce allogeneic T cell proliferation when first co-cultured with 10% of PUVA-treated cells. Our experimental design provides a novel insight into the real action of 8-MOP and UVA light on dendritic cell biology, suggesting an additional mechanism by which 8-MOP and UVA light exposure may influence immune responses.