Characterizing Metabolic Shifts in Septic Murine Kidney Tissue Using 2P-FLIM for Early Sepsis Detection.

Area of Science:

• Biomedical Optics
• Metabolic Imaging
• Renal Physiology

Background:

• Sepsis significantly alters cellular metabolism, particularly in the kidneys.
• Existing methods for assessing kidney metabolism in sepsis are limited.
• Endogenous coenzymes like NADH and FAD are crucial metabolic indicators.

Purpose of the Study:

• To investigate the utility of two-photon excited fluorescence lifetime imaging (2P-FLIM) for analyzing cell metabolism in mouse kidney sections.
• To differentiate metabolic profiles of healthy, acutely septic, and chronically septic mouse kidneys.
• To explore 2P-FLIM's potential for early sepsis diagnosis and treatment monitoring.

Main Methods:

• Utilized 2P-FLIM to image endogenous nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) in thin mouse kidney sections.
• Developed an adapted measurement routine with specific excitation wavelengths and detection ranges for NADH and FAD.
• Analyzed fluorescence lifetime signatures from healthy, acute sepsis, and chronic sepsis mouse kidney samples.

Main Results:

• Healthy kidney slices exhibited distinct fluorescence lifetime signatures compared to those with acute sepsis.
• Acute sepsis induced a metabolic shift from oxidative phosphorylation to glycolysis in outer cortical tubular cells.
• Metabolic profiles in chronic sepsis indicated a return towards oxidative phosphorylation.

Conclusions:

• 2P-FLIM is a powerful tool for investigating cell metabolism in thin tissue sections, particularly the kidney.
• Distinct metabolic alterations in the kidney correlate with sepsis severity and stage.
• 2P-FLIM shows promise for early sepsis detection and monitoring therapeutic metabolic recovery.