Diabetes mellitus als Risikofaktor des Pankreasadeno- karzinoms: Einfluss von Hyperglykämie auf den Phänotyp von Makrophagen und ihre Wirkung auf Pankreasgangepithelzellen

With less than 4 %, pancreatic ductal adenocarcinoma (PDAC) represents a small share in newly detected cancers but is among the few tumour entities with increasing incidence and mortality. By the year of 2030, PDAC is predicted to be the second most lethal neoplasia in western countries. Due to the lack of specific early symptoms, 80% of the patients are diagnosed in late tumour stages, leaving palliative treatment as the only therapeutic option. Besides chronic inflammation, obesity and type 2 diabetes mellitus (T2DM) - both associated with hyperglycaemia - are risk factors contributing to the initiation and progression of PDAC. However, underlying mechanisms are not yet fully understood. It is known that already precursor lesions are characterised by an inflammatory stroma. Macrophages, representing one of the largest immune cell populations within this stroma, impact on pancreatic ductal epithelial cells (PDEC) by promoting their malignant progression. Previous studies showed that high glucose levels influence the phenotype of macrophages, leading to the question whether these changes in macrophages’ phenotype in a T2DM-related inflammatory and hyperglycaemic microenvironment further facilitate malignancy-associated alterations in PDEC. In order to address this question, both, macrophages differentiated from human monocytes and H6c7-pBp and H6c7-kras cells mimicking benign and premalignant PDEC, were analysed after direct coculture under hyperglycaemia and compared to normoglycemic conditions. In macrophages, IL-6 levels were most strongly elevated, along with other pro-inflammatory cytokines such as IL-8 and of TNF-. In PDEC, the pro-inflammatory hyperglycaemic microenvironment enhanced the acquisition of tumourigenesis-associated alterations: Epithelial-Mesenchymal-Transition (EMT) and the acquisition of cancer stemness properties were promoted; and common soluble mediators of these two phenomena were increased in their expression levels as well. Many of these alterations were slightly more pronounced in H6c7-kras cells, however, also benign PDEC cells were shown to be driven into malignant progression through the complex interplay of an inflammatory hyperglycaemic surrounding. This underlines the importance of early intervention options in high-risk patients. Blockade of TGF- signalling partially reversed the above-mentioned changes in PDEC, as did the blockade of IL-6 trans-signalling via sgp130Fc, suggesting a partial involvement of these factors in inflammation and hyperglycaemia driven acquisition of malignancy-associated alterations and pointing to possible therapeutic points of attack. Overall, the current study corroborates the importance of the interplay of macrophages and hyperglycaemia as a leading contributor to the acquisition of malignancy-associated alterations in PDEC. It gives a new understanding of how metabolic disorders such as T2DM and obesity might initiate and promote PDAC. A better understanding of this is essential to foster ideas for potential early therapeutic intervention in high-risk patients - the current study pointing out an early anti-inflammatory therapy as one promising option in PDAC prevention

Initiation of Pancreatic Cancer: The Interplay of Hyperglycemia and Macrophages Promotes the Acquisition of Malignancy-Associated Properties in Pancreatic Ductal Epithelial Cells

Pancreatic ductal adenocarcinoma (PDAC) is still one of the most aggressive solid malignancies with a poor prognosis. Obesity and type 2 diabetes mellitus (T2DM) are two major risk factors linked to the development and progression of PDAC, both often characterized by high blood glucose levels. Macrophages represent the main immune cell population in PDAC contributing to PDAC development. It has already been shown that pancreatic ductal epithelial cells (PDEC) undergo epithelial-mesenchymal transition (EMT) when exposed to hyperglycemia or macrophages. Thus, this study aimed to investigate whether concomitant exposure to hyperglycemia and macrophages aggravates EMT-associated alterations in PDEC. Exposure to macrophages and elevated glucose levels (25 mM glucose) impacted gene expression of EMT inducers such as IL-6 and TNF-α as well as EMT transcription factors in benign (H6c7-pBp) and premalignant (H6c7-kras) PDEC. Most strikingly, exposure to hyperglycemic coculture with macrophages promoted downregulation of the epithelial marker E-cadherin, which was associated with an elevated migratory potential of PDEC. While blocking IL-6 activity by tocilizumab only partially reverted the EMT phenotype in H6c7-kras cells, neutralization of TNF-α by etanercept was able to clearly impair EMT-associated properties in premalignant PDEC. Altogether, the current study attributes a role to a T2DM-related hyperglycemic, inflammatory micromilieu in the acquisition of malignancy-associated alterations in premalignant PDEC, thus providing new insights on how metabolic diseases might promote PDAC initiation

Chitosan nanoparticles as antigen vehicles to induce effective tumor specific T cell responses

Cancer vaccinations sensitize the immune system to recognize tumor-specific antigens de novo or boosting preexisting immune responses. Dendritic cells (DCs) are regarded as the most potent antigen presenting cells (APCs) for induction of (cancer) antigen-specific CD8+ T cell responses. Chitosan nanoparticles (CNPs) used as delivery vehicle have been shown to improve anti-tumor responses. This study aimed at exploring the potential of CNPs as antigen delivery system by assessing activation and expansion of antigen-specific CD8+ T cells by DCs and subsequent T cell-mediated lysis of pancreatic ductal adenocarcinoma (PDAC) cells. As model antigen the ovalbumin-derived peptide SIINFEKL was chosen. Using imaging cytometry, intracellular uptake of FITC-labelled CNPs of three different sizes and qualities (90/10, 90/20 and 90/50) was demonstrated in DCs and in pro- and anti-inflammatory macrophages to different extents. While larger particles (90/50) impaired survival of all APCs, small CNPs (90/10) were not toxic for DCs. Internalization of SIINFEKL-loaded but not empty 90/10-CNPs promoted a pro-inflammatory phenotype of DCs indicated by elevated expression of pro-inflammatory cytokines. Treatment of murine DC2.4 cells with SIINFEKL-loaded 90/10-CNPs led to a marked MHC-related presentation of SIINFEKL and enabled DC2.4 cells to potently activate SIINFEKL-specific CD8+ OT-1 T cells finally leading to effective lysis of the PDAC cell line Panc-OVA. Overall, our study supports the suitability of CNPs as antigen vehicle to induce potent anti-tumor immune responses by activation and expansion of tumor antigen-specific CD8+ T cells