Identifying the Cellular Tipping Point of Inflammation with Raman Spectroscopy

Identification of the Cellular Tipping Point in the Inflammation Model of LPS-Induced RAW264.7 Macrophages Through Raman Spectroscopy and the Dynamical Network Biomarker Theory

Scientists from the University of Toyama have identified the precise moment when inflammation in immune cells shifts from an early response to a full-blown state, as detailed in a recent study published in Molecules.

Scientists have long studied the beginning and end stages of inflammation, but the critical transition point, the “tipping point”, has remained unclear. To approach this task, the team used RAW264.7 mouse macrophages, a standard model for studying immune responses, then stimulated these cells with lipopolysaccharide (LPS), a molecule that mimics bacterial infection. The group then tracked molecular changes every two hours for 24 hours using Raman spectroscopy, a non-destructive spectroscopic technique that provides complex molecular information.

For the Raman microscope system, the team used the Cobolt Samba 532 nm laser as the excitation source, with the intensity of the laser adjusted between 0.2 and 20 mW at the sample point.

The team discovered that 14 hours after LPS stimulation, the cells hit a tipping point,  a moment of maximum fluctuation before settling into a full-blown inflammatory state. Further, by applying Dynamic Network Biomarker Theory (DNB), they were able to identify tryptophan (an amino acid) as a key biomarker of this transition. Tryptophan’s fluctuating levels at the 14-hour mark suggest it plays a crucial role in regulating inflammation.

The study opens the door to early intervention strategies for inflammatory diseases. Being able to detect early warning signals at tipping points in inflammatory responses will provide novel insights for future studies on inflammatory reactions.