Distinct human Langerhans cell subsets orchestrate reciprocal functions and require different developmental...

Area of Science:

• Immunology
• Dermatology
• Cell Biology

Background:

• Langerhans cells (LCs) are crucial for skin homeostasis.
• The heterogeneity of LC populations has been long recognized but not fully elucidated.

Purpose of the Study:

• To identify and characterize distinct subsets of human Langerhans cells.
• To understand the developmental regulation and functional differences between these subsets.

Main Methods:

• Single-cell RNA sequencing
• Mass cytometry
• Analysis of LCs from human skin epidermis and CD34+ hemopoietic stem cells (HSC-LCs) differentiation.

Main Results:

• Identified two steady-state (LC1, LC2) and two activated human LC subsets.
• EGR1 and Notch signaling pathways regulate LC1/LC2 differentiation.
• LC1 function in innate immunity and antigen processing; LC2 resemble monocytes/myeloid dendritic cells, involved in immune responses.
• LC1 are stable in inflammation; LC2 are activated by inflammation and express immunosuppressive molecules.

Conclusions:

• Distinct human LC subsets possess unique functional properties and developmental trajectories.
• Understanding LC subset heterogeneity is key to deciphering skin immune regulation.