Biomedical nanoparticles modulate specific CD4(+) T cell stimulation by inhibition of antigen processing in dendritic cells

Understanding how nanoparticles may affect immune responses is an essential prerequisite to developing novel clinical applications. To investigate nanoparticle-dependent outcomes on immune responses, dendritic cells (DCs) were treated with model biomedical poly(vinylalcohol)-coated super-paramagnetic iron oxide nanoparticles (PVA-SPIONs). PVA-SPIONs uptake by human monocyte-derived DCs (MDDCs) was analyzed by flow cytometry (FACS) and advanced imaging techniques. Viability, activation, function, and stimulatory capacity of MDDCs were assessed by FACS and an in vitro CD4(+) T cell assay. PVA-SPION uptake was dose-dependent, decreased by lipopolysaccharide (LPS)-induced MDDC maturation at higher particle concentrations, and was inhibited by cytochalasin D pre-treatment. PVA-SPIONs did not alter surface marker expression (CD80, CD83, CD86, myeloid/plasmacytoid DC markers) or antigen-uptake, but decreased the capacity of MDDCs to process antigen, stimulate CD4(+) T cells, and induce cytokines. The decreased antigen processing and CD4(+) T cell stimulation capability of MDDCs following PVA-SPION treatment suggests that MDDCs may revert to a more functionally immature state following particle exposure

Adhesion G protein-coupled receptors: opportunities for drug discovery

The seminal discovery of the novel activation mechanism of Adhesion GPCRs (aGPCRs)1,2, together with their strong and growing links to disease from human genetics and pre-clinical research, has prompted a rapid reconsideration of this unique family of receptors for classical drug discovery. However, while acknowledged as a sub-family of GPCRs by the IUPHAR3, these receptors are anything but classical with their complex gene structures, large multi-domain N-termini, autocatalytic cleavage and tethered ligands. Initially thought to have a purely structural role, the increasing functional complexity of this GPCR sub-family and the many, potentially unique mechanisms of modulation challenges the way we have perceived this protein class until now. Significantly, if 50% of non-sensory GPCRs are unexploited as drug targets4, this figure reaches 100% for aGPCRs so the potential to develop novel therapies could be substantial5. Here, we discuss the unique opportunities and challenges brought by aGPCRs in the context of drug discovery programs naturally starting with target identification then extending to target validation, assay building and safety considerations