A spectroscopic approach enables the differentiation of macrophages without interfering with their natural environment.

Macrophages are indispensable players in our immune system. They recognize, engulf, and destroy pathogens, and they play a crucial role in clearing cellular damage and healing tissue. A young research team at Leibniz IPHT is using Raman spectroscopy to differentiate various types of these immune cells in a non-invasive manner and without the use of labeling agents.

“We were particularly interested in gaining a better understanding of the intracellular differences between pro-inflammatory M1 macrophages and healing-associated M2 macrophages,” explains Max Naumann. “While one type actively fights infections, the other supports the healing process.” The specific characterization of these cells can not only provide insights into disease states, but also serve as an indicator of the course and severity of an illness.

Max Naumann and Natalie Arend planned the study together with Prof. Dr. Ute Neugebauer in her Department of Clinical Spectroscopic Diagnostics and also carried out the measurements. Max Naumann is pursuing his doctorate at Leibniz IPHT and the Center for Sepsis Control and Care at Jena University Hospital; Natalie Arend has since taken up a position in industry after successfully completing her PhD.

Light as the Key to Cell Analysis

The team relied on Raman spectroscopy, a technique based on the scattering of light by molecules. It allows cells to be examined in their natural state without damaging them. By analyzing macrophages derived from human blood monocytes, the researchers identified significant differences in the spectral signatures of the various macrophage types.

Indicators of Disease

“The spectral signatures are crucial for distinguishing macrophage states without labels. They provide us with a new understanding of their role in different disease processes,” explains Rustam Guliev, an expert in chemometrics and the analysis of hyperspectral images. The mathematician and computer scientist came to Jena from the Russian Academy of Sciences in Moscow through the European training network IMAGE-IN, supported by an EU Marie Skłodowska-Curie fellowship. Early-career researchers in the IMAGE-IN network work on advanced imaging and data analysis methods for infection research.

From the Laboratory to Clinical Practice

The study shows that Raman imaging is a precise tool for the rapid characterization of immune cell types. “Our results demonstrate the potential of Raman imaging as a powerful instrument in immune cell research,” concludes Ute Neugebauer. Before the method can be integrated into clinical practice, however, further research is required—particularly with regard to applications in complex organ systems and, possibly later, in living organisms.

Combining this advanced spectroscopic technique with biological knowledge could expand our understanding of the immune system and significantly advance the development of new treatment strategies for a wide range of diseases, including inflammatory conditions, autoimmune diseases, and cancer.

 

Original Publication: Naumann, M.; Arend, N.; Guliev, R.R.; Kretzer, C.; Rubio, I.; Werz, O.; Neugebauer, U. Label-Free Characterization of Macrophage Polarization Using Raman Spectroscopy . Int. J. Mol. Sci. 2023, 24,824. https://doi. org/10.3390/ ijms24010824