Maturation of Monocyte-Derived DCs Leads to Increased Cellular Stiffness, Higher Membrane Fluidity, and Changed Lipid Composition

Abstract

Dendritic cells (DCs) are professional antigen-presenting cells of the immune system. Upon sensing pathogenic material in their environment, DCs start to mature, which includes cellular processes, such as antigen uptake, processing and presentation, as well as upregulation of costimulatory molecules and cytokine secretion. During maturation, DCs detach from peripheral tissues, migrate to the nearest lymph node, and find their way into the correct position in the net of the lymph node microenvironment to meet and interact with the respective T cells. We hypothesize that the maturation of DCs is well prepared and optimized leading to processes that alter various cellular characteristics from mechanics and metabolism to membrane properties. Here, we investigated the mechanical properties of monocyte-derived dendritic cells (moDCs) using real-time deformability cytometry to measure cytoskeletal changes and found that mature moDCs were stiffer compared to immature moDCs. These cellular changes likely play an important role in the processes of cell migration and T cell activation. As lipids constitute the building blocks of the plasma membrane, which, during maturation, need to adapt to the environment for migration and DC-T cell interaction, we performed an unbiased high-throughput lipidomics screening to identify the lipidome of moDCs. These analyses revealed that the overall lipid composition was significantly changed during moDC maturation, even implying an increase of storage lipids and differences of the relative abundance of membrane lipids upon maturation. Further, metadata analyses demonstrated that lipid changes were associated with the serum low-density lipoprotein (LDL) and cholesterol levels in the blood of the donors. Finally, using lipid packing imaging we found that the membrane of mature moDCs revealed a higher fluidity compared to immature moDCs. This comprehensive and quantitative characterization of maturation associated changes in moDCs sets the stage for improving their use in clinical application.

The Contact Allergen NiSO4 Triggers a Distinct Molecular Response in Primary Human Dendritic Cells Compared to Bacterial LPS

“…These findings were explained by an altered lipid class composition in mature MoDCs. Strikingly the performed lipidomic analysis also disclosed reduced cholesterolester levels in mature MoDCs ( 54 ), which supports our findings of cellular cholesterol depletion. However, the role and fate of cholesterol during DC maturation is to date not fully understood.…”

Phospholipid exchange shows insulin receptor activity is supported by both the propensity to form wide bilayers and ordered domains (rafts)

“…Thus, the results of lipid exchange studies in cells strongly favor a model of IR activity regulation where a combination of increased bilayer width and a relative inaccessibility of phosphatases in Lo domains favor IR activation. It is possible that alterations of lipid by diet and cell changes related to differentiation [54] Figure 9: Schematic representation of the hypothesis for the effect of altering lipid composition upon IR activity. Green represents Ld domains, red Lo domains.…”

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“…In particular, single cell mechanics is of interest in modern cell biology and immunology. It allows prediction of pathogen infected cells [150], maturation stage of dendritic cells [151,152], and T cell and antigen-presenting cell interactions [153,154]. Cell mechanics has been hypothesized to alter as an adaptation mechanism to microgravity since it might be correlated to cytoskeleton remodeling [55,56,58].…”