Colorectal cancer (CRC) results from the accumulation of both genetic and epigenetic alterations of the genome. However, also the formation of an inflammatory milieu plays a pivotal role in tumor development and progression. Dendritic cells (DCs) play a relevant role in tumor by exerting differential pro-tumorigenic and anti-tumorigenic functions, depending on the local milieu. Quantitative and functional impairments of DCs have been widely observed in several types of cancer, including CRC, representing a tumor-escape mechanism employed by cancer cells to elude host immunosurveillance.Understanding the interactions between DCs and tumors is important for comprehending the mechanisms of tumor immune surveillance and escape, and provides novel approaches to therapy of cancer. This review summarizes updated information on the role of the DCs in colon cancer development and/or progression.

Human aging is associated with immunosenescence, a process characterized by alterations in numerical and functional features of immune system components. Dendritic cells (DCs) are the main antigen-presenting cells, playing a pivotal role in adaptive and innate immunity. Therefore, we investigated the distribution of human circulating DCs throughout the life, in order to contribute to the knowledge of the physiological background underlying the aging of immune system. Cytofluorimetric analysis of peripheral blood samples by all-aged healthy population showed a significant decrease of circulating DCs and of their two main subsets among age. This reduction was limited to the plasmacytoid cell subtype when young and old subjects were analyzed separately. The analysis of circulating Treg cell number in a cohort of the subjects showed a significant reduction with increasing age and a positive significant correlation to myeloid or plasmacytoid absolute numbers. In conclusion, this work provides a large set of data of normal reference values of peripheral blood dendritic cells in healthy population suitable for comparative clinical studies concerning pathological immune dysfunctions.

There is increasing interest in the development of cost-effective techniques for the quantification of DNA methylation biomarkers. We analyzed 90 samples of surgically resected colorectal cancer tissues for APC and CDKN2A promoter methylation using methylation sensitive-high resolution melting (MS-HRM) and pyrosequencing. MS-HRM is a less expensive technique compared with pyrosequencing but is usually more limited because it gives a range of methylation estimates rather than a single value. Here, we developed a method for deriving single estimates, rather than a range, of methylation using MS-HRM and compared the values obtained in this way with those obtained using the gold standard quantitative method of pyrosequencing. We derived an interpolation curve using standards of known methylated/unmethylated ratio (0%, 12.5%, 25%, 50%, 75%, and 100% of methylation) to obtain the best estimate of the extent of methylation for each of our samples. We observed similar profiles of methylation and a high correlation coefficient between the two techniques. Overall, our new approach allows MS-HRM to be used as a quantitative assay which provides results which are comparable with those obtained by pyrosequencing.

SummaryExtracorporeal 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 PUVAtreated 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.

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