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From the 1980s, extracorporeal photochemotherapy (ECP) has been shown to be effective in a variety of pathological conditions such as erythrodermic cutaneous T-cell lymphoma, autoimmune diseases, solid organ allograft rejection and graft versus host disease. To date, ECP represents a non-aggressive immune modulatory therapy with a low spectrum of toxicity. ECP reduces the alloreactivity promoting the immune tolerance to self. At the same time, it allows the maintenance of immune response integrity of both naive and memory T-cells. However, the molecular mechanisms of action by which ECP exerts its therapeutic activity are still under investigation. Here, we review molecular mechanisms and clinical applications involved in ECP. The outcome of ECP is difficult due to the lack of reliable predictor factors for the selection of patients and their adequate follow-up. Since the study of such predictors is important, we also describe some biological markers that enable us to investigate the clinical management of the patients considered for the use of ECP., (© 2014 The Authors. Therapeutic Apheresis and Dialysis © 2014 International Society for Apheresis.)

Genome-wide association studies have revealed several genes predisposing to autoimmunity, however, concordance rates in monozygotic twins are significantly below 50% for several autoimmune diseases. The limited presence of a strong genetic association only in some patients supports that other non-genetic mechanisms are active in these pathologies. Epigenetic modifications such as DNA methylation, histone modification, and microRNA signaling regulate gene expression and are sensitive to external stimuli and they might be as bridging between genetic and environmental factors. Some evidence has highlighted the involvement of epigenetic alterations in the pathogenesis of various autoimmune diseases giving rise to great expectations among clinicians and researchers. The direct role of these alterations in the initiation/progression of autoimmune diseases is still unclear. The knowledge in depth of these pathogenic and epigenetic mechanisms will increase the possibility of the control and/or prevention of autoimmune diseases through the use of drugs that target epigenetic pathways. Moreover, we could use epigenetic-related biomarkers to follow this complicated framework (for example H3K4me3 and miRNA-155 are among those proposed biomarkers). This article reviews current understanding of the epigenetic involvement in the field of autoimmune diseases especially in systemic lupus erythematosus, rheumatoid arthritis, sclerosis multiple and type 1 diabetes., (Copyright © 2015 Elsevier Inc. All rights reserved.)