Real-time dynamics of neutrophil clustering in response to phototoxicity-induced cell death and tissue damage in mouse ear dermis

ABSTRACT

Neutrophils are highly motile innate immune cells; they actively migrate in response to inflammatory signals. Using two-photon intravital microscopy, we discovered that neutrophils form stable clusters upon phototoxicity at a certain threshold. Without significant damage to the collagen structure of mouse dermis, neutrophils aggregated together with nearby neutrophils. Surprisingly, this in situ neutrophil clustering resulted in rigorous changes of migratory direction. The density of residing neutrophils was also a critical factor affecting clustering. Additionally, we found that the triggering point of neutrophil aggregation was correlated with the structure of the extracellular matrix in the ear dermis, where autofluorescence was strongly observed. This swarming behavior of neutrophils may reflect an unknown communication mechanism of neutrophils during migration under sterile injury.

KEYWORDS:

• Neutrophil
• migration
• two-photon microscopy
• intravital imaging
• phototoxicity

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Additional information

Funding

This study was supported by the faculty research grant of Yonsei University College of Medicine [6-2016-0132] and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) [2016R1A2B4008199] (Y-M. H.).