Real-Time Volatile Metabolomics Analysis of Dendritic Cells

Dendritic cells (DCs)actively sample and present antigen to cellsof the adaptive immune system and are thus vital for successful immunecontrol and memory formation. Immune cell metabolism and functionare tightly interlinked, and a better understanding of this interactionoffers potential to develop immunomodulatory strategies. However,current approaches for assessing the immune cell metabolome are oftenlimited by end-point measurements, may involve laborious sample preparation,and may lack unbiased, temporal resolution of the metabolome. In thisstudy, we present a novel setup coupled to a secondary electrosprayionization-high resolution mass spectrometric (SESI-HRMS) platformallowing headspace analysis of immature and activated DCs in real-timewith minimal sample preparation and intervention, with high technicalreproducibility and potential for automation. Distinct metabolic signaturesof DCs treated with different supernatants (SNs) of bacterial cultureswere detected during real-time analyses over 6 h compared to theirrespective controls (SN only). Furthermore, the technique allowedfor the detection of C-13-incorporation into volatile metabolites,opening the possibility for real-time tracing of metabolic pathwaysin DCs. Moreover, differences in the metabolic profile of nai''veand activated DCs were discovered, and pathway-enrichment analysisrevealed three significantly altered pathways, including the TCA cycle,alpha-linolenic acid metabolism, and valine, leucine, and isoleucinedegradation.

Automated summary

In this study, a novel setup coupled with a secondary electrospray ionization-high resolution mass spectrometric (SESI-HRMS) platform was developed to analyze the real-time metabolic changes in immature and activated dendritic cells (DCs). Distinct metabolic signatures were detected in DCs treated with different supernatants of bacterial cultures, and differences in the metabolic profile of naive and activated DCs were discovered. Pathway-enrichment analysis revealed three significantly altered pathways.