Lung megakaryocytes are immune modulatory cells

Area of Science:

• Immunology
• Hematology
• Cell Biology

Background:

• Platelets, primarily known for thrombosis, also possess immune functions.
• Megakaryocytes (Mks), the source of platelets, were traditionally considered bone marrow-resident.
• Lung Mks (MkL) exhibit distinct immune gene expression compared to bone marrow Mks.

Purpose of the Study:

• To define the immune functions of lung Mks (MkL).
• To investigate the plasticity of Mk immune phenotype based on tissue environment.

Main Methods:

• Single-cell RNA sequencing of bone marrow and lung myeloid cells.
• Imaging and conventional flow cytometry.
• In vitro and in vivo assays including antigen presentation and T cell activation studies.

Main Results:

• Lung Mks (MkL) display gene expression patterns similar to antigen-presenting cells.
• Mk immune phenotype is plastic, influenced by tissue microenvironment (e.g., IL-33).
• MkL internalize and process antigens and pathogens, inducing CD4+ T cell activation via MHC II.

Conclusions:

• Lung Mks (MkL) possess significant immune functions, acting as antigen-presenting cells.
• Tissue microenvironment plasticity shapes Mk immune capabilities.
• MkL play key immune regulatory roles, partly dictated by their tissue of residence.