Session: Session 5
Development of Mass Spectrometry Imaging on skeletal muscle to characterize the local pro-inflammatory and pro-resolution lipid responses in a vaccination context.
Objectives
Vaccine reactogenicity is well documented at the clinical level, but the mechanisms involved at the local or systemic level are still poorly understood. Muscle tissue, where most vaccines are administered, is the first site of interaction between the vaccine formulation and host immune cells. The study of early molecular events at the injection site is crucial for understanding the local response to vaccines. In this work, we report a standardized workflow from injection of vaccine formulations into rabbit muscle to analysis by spatial metabolomics and histological staining to understand the role of lipids involved in inflammation and its resolution in striated muscle tissue.
Methods
We standardized the localization of the injection site in the rabbit quadriceps femoris muscle. We then applied hematoxylin-eosin (HE) staining and optimized Desorption ElectroSpray Ionization MSI (DESI-MSI) on a QExactive mass spectrometer (Thermo Fisher) to detect lipids from muscle samples embedded in Tissue-Tek® Optimum Cutting Temperature (OCT) compound. Data were analyzed using the Cardinal package.
Results
Using this methodology, we were able to establish a data analysis strategy to detect most of the lipids involved in pro-inflammation and pro-resolution. The comparison between DESI and HE showed that the lipid distribution co-localized with the inflammatory pattern observed at the histopathological level. We were also able to gain insight into some precursors. AA, 15/11HETE and 5/11 HEPE were distributed over the spatial tissue morphology in a time-dependent manner. And we observed a significant decrease of 5/11HEPE and 15/11HETE lipids from day 1 to day 4.
Conclusion
This work could contribute to a better definition of the spatial distribution and kinetics of lipids, at the site of vaccine injection, of key molecules involved in a vaccine mode of action. The MS imaging applied to vaccinology could pave the way to a better understanding of vaccine reactogenicity.
Vaccine reactogenicity is well documented at the clinical level, but the mechanisms involved at the local or systemic level are still poorly understood. Muscle tissue, where most vaccines are administered, is the first site of interaction between the vaccine formulation and host immune cells. The study of early molecular events at the injection site is crucial for understanding the local response to vaccines. In this work, we report a standardized workflow from injection of vaccine formulations into rabbit muscle to analysis by spatial metabolomics and histological staining to understand the role of lipids involved in inflammation and its resolution in striated muscle tissue.
Methods
We standardized the localization of the injection site in the rabbit quadriceps femoris muscle. We then applied hematoxylin-eosin (HE) staining and optimized Desorption ElectroSpray Ionization MSI (DESI-MSI) on a QExactive mass spectrometer (Thermo Fisher) to detect lipids from muscle samples embedded in Tissue-Tek® Optimum Cutting Temperature (OCT) compound. Data were analyzed using the Cardinal package.
Results
Using this methodology, we were able to establish a data analysis strategy to detect most of the lipids involved in pro-inflammation and pro-resolution. The comparison between DESI and HE showed that the lipid distribution co-localized with the inflammatory pattern observed at the histopathological level. We were also able to gain insight into some precursors. AA, 15/11HETE and 5/11 HEPE were distributed over the spatial tissue morphology in a time-dependent manner. And we observed a significant decrease of 5/11HEPE and 15/11HETE lipids from day 1 to day 4.
Conclusion
This work could contribute to a better definition of the spatial distribution and kinetics of lipids, at the site of vaccine injection, of key molecules involved in a vaccine mode of action. The MS imaging applied to vaccinology could pave the way to a better understanding of vaccine reactogenicity.