Epigenetic Changes Induced by Maternal Factors during Fetal Life: Implication for Type 1 Diabetes.

Organ-specific autoimmune diseases, such as type 1 diabetes, are believed to result from T-cell-mediated damage of the target tissue. The immune-mediated tissue injury, in turn, is known to depend on complex interactions between genetic and environmental factors. Nevertheless, the mechanisms whereby environmental factors contribute to the pathogenesis of autoimmune diseases remain elusive and represent a major untapped target to develop novel strategies for disease prevention. Given the impact of the early environment on the developing immune system, epigenetic changes induced by maternal factors during fetal life have been linked to a likelihood of developing an autoimmune disease later in life. In humans, DNA methylation is the epigenetic mechanism most extensively investigated. This review provides an overview of the critical role of DNA methylation changes induced by prenatal maternal conditions contributing to the increased risk of immune-mediated diseases on the offspring, with a particular focus on T1D. A deeper understanding of epigenetic alterations induced by environmental stressors during fetal life may be pivotal for developing targeted prevention strategies of type 1 diabetes by modifying the maternal environment.

Extracellular Vesicles Released by Enterovirus-Infected EndoC-ßH1 Cells Mediate Non-Lytic Viral Spread.

While human enteroviruses are generally regarded as a lytic virus, and persistent non-cytolytic enterovirus infection in pancreatic beta cells has been suspected of playing a role in type 1 diabetes pathogenesis. However, it is still unclear how enteroviruses could exit the pancreatic beta cell in a non-lytic manner. This study aimed to investigate the role of beta cell-derived extracellular vesicles (EVs) in the non-lytic enteroviral spread and infection. Size-exclusion chromatography and antibody-based immunoaffinity purification were used to isolate EVs from echovirus 16-infected human beta EndoC-ßH1 cells. EVs were then characterized using transmission electron microscopy and Multiplex Bead-Based Flow Cytometry Assay. Virus production and release were quantified by 50% cell culture infectious dose (CCID50) assay and qRT-PCR. Our results showed that EVs from echovirus 16-infected EndoC-ßH1 cells harbor infectious viruses and promote their spread during the pre-lytic phase of infection. Furthermore, the EVs-mediated infection was not inhibited by virus-specific neutralizing antibodies. In summary, this study demonstrated that enteroviruses could exit beta cells non-lytically within infectious EVs, thereby thwarting the access of neutralizing antibodies to viral particles. These data suggest that enterovirus transmission through EVs may contribute to viral dissemination and immune evasion in persistently infected beta cells.

Critical parameters in blood processing for T-cell assays: validation on ELISpot and tetramer platforms.

Assays detecting antigen (Ag)-specific T-cell responses in immune-mediated processes are increasingly employed to understand disease pathogenesis and immune staging. The quantity and quality of starting peripheral blood mononuclear cell (PBMC) preparations are important factors in the performance of such assays. We therefore compared final PBMC yield and function by modifying parameters at the blood drawing, storage and processing steps. While drawing blood in vacuum-driven tubes or syringes and separating PBMCs on density gradients using standard or membrane (Leucosep) tubesmade no difference, storing tubes for 18 h without any agitation led to PBMC preparations contaminated with granulocytes and decreased interferon (IFN)-gamma enzyme-linked immunospot (ELISpot) responses. Even agitated blood showed a trend towards reduced ELISpot responses and increased human leukocyte Ag (HLA) multimer readouts when stored for 18 h compared to 3 h. These changes were reduced by diluting blood prior to storage. Washing PBMCs with media containing 10% human serum increased PBMC yields by 40.5%, without affecting ELISpot responses and multimer counts. However, washes with > 10% human serum decreased multimer counts, with no additional improvement in PBMC yields. These findings may be relevant for optimizing and harmonizing PBMC processing procedures for T-cell assays.