Synthesis and Characterization of Ceramide-Containing Liposomes as Membrane Models for Different T Cell...

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• A precise balance between regulatory T cells (Treg) and conventional CD4+ T cells (Tconv) is crucial for immune homeostasis and pathogen defense.
• Sphingolipid metabolism significantly influences this Treg/Tconv balance, yet its precise role in T cell biology requires further elucidation.
• Understanding the tools and mechanisms governing sphingolipid metabolism in T cells is essential for advancing the field.

Purpose of the Study:

• To investigate the role of sphingolipid metabolism, specifically ceramide content, in modulating the balance between mouse T regulatory (Treg) and T conventional (Tconv) cells.
• To develop and utilize a reductionist liposomal membrane model system mimicking the plasma membrane ceramide composition of Treg and Tconv cells.
• To assess the impact of varying ceramide content in liposomal models on primary mouse splenocyte viability and function in vitro.

Main Methods:

• Creation of reductionist liposomal membrane models with defined ceramide content to mimic mouse Treg and Tconv plasma membranes.
• Quantification of azide-functionalized ceramide incorporation into liposomes, correlating with liposomal ceramide levels.
• In vitro incubation of primary mouse splenocytes with various liposomal preparations to evaluate effects on cell viability and activation status.

Main Results:

• Liposome membrane capacity for incorporating external azide-functionalized ceramide showed a positive correlation with the liposomes' inherent ceramide content.
• Liposomal preparations significantly impacted primary mouse splenocyte viability in vitro, particularly when added to resting cells.
• Liposomes enriched with high amounts of C16-ceramide demonstrated the most potent effect in maintaining the viability of resting splenocytes.

Conclusions:

• Differences in ceramide incorporation into Treg and Tconv cells likely reflect inherent variations in their plasma membrane ceramide composition.
• The study provides a novel liposomal model system to investigate ceramide's role in T cell biology.
• Findings suggest that specific ceramide species, like C16-ceramide, may play a protective role in maintaining T cell viability, especially in resting states.