Label-free imaging of M1 and M2 macrophage phenotypes in the human dermis in vivo using two-photon excited FLIM
- Charité - Universitätsmedizin Berlin, Germany
- Lomonosov Moscow State University, Russian Federation
Abstract
Macrophages (ΜΦs) are important immune effector cells that promote (M1 ΜΦs) or inhibit (M2 ΜΦs) inflammation and are involved in numerous physiological and pathogenic immune responses. Their precise role and relevance, however, is not fully understood for lack of non-invasive quantification methods. Here, we show that two-photon excited fluorescence lifetime imaging (TPE-FLIM), a label-free non-invasive method, can visualize ΜΦs in the human dermis in vivo. We demonstrate in vitro that human dermal ΜΦs exhibit specific TPE-FLIM properties that distinguish them from the main components of the extracellular matrix and other dermal cells. We visualized ΜΦs, their phenotypes and phagocytosis in the skin of healthy individuals in vivo using TPE-FLIM. Additionally, machine learning identified M1 and M2 MФs with a sensitivity of 0.88±0.04 and 0.82±0.03 and a specificity of 0.89±0.03 and 0.90±0.03, respectively. In clinical research, TPE-FLIM can advance the understanding of the role of MФs in health and disease.
Data availability
The data have been deposited in Dryad:
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Macrophage FLIM raw dataDryad Digital Repository, doi:10.5061/dryad.8gtht76q2.
Article and author information
Author details
Funding
Foundation for Skin Physiology
- Marius Kröger
- Johannes Schleusener
- Martina C Meinke
- Jürgen Lademann
- Maxim E Darvin
Russian Science Foundation (19-75-10077)
- Evgeny A Shirshin
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Human subjects: Positive votes for the experiments have been obtained from the ethics committee of the Charité - Universitätsmedizin Berlin (EA1/078/18, EA4/193/18, EA1/141/12), which were conducted according to the Declaration of Helsinki (59th WMA General Assembly, Seoul, October 2008).
Copyright
© 2022, Kröger et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Label-free imaging of M1 and M2 macrophage phenotypes in the human dermis in vivo using two-photon excited FLIM
eLife 11:e72819.
https://doi.org/10.7554/eLife.72819
