Macrophage Recognition of Environmental Particles and Crystals

Today, our bodies are exposed to various environmental particles, such as PM2.5, silica, and engineered nanoparticles. When these particles enter the body, many are recognized by macrophages and trigger inflammation, which can lead to incurable diseases. For instance, silica and asbestos are well known to cause silicosis and mesothelioma, respectively. A certain type of carbon nanotubes, as prominent products of nanotechnology, may exhibit asbestos-like pathogenicity. The impact of microplastics on human health has recently raised concerns.

We are interested in understanding how macrophages recognize such inorganic particles. So far, we have identified the class B scavenger receptor SR-B1 for silica （Tsugita et al., Cell Rep., 2017）, and Tim4 and Siglec-14 for carbon nanotubes and polystyrene microplastics(Omori et al., Cell Rep., 2021; Yamaguchi et al., Nature Nanotechnol.,.2023; Kuroiwa et al.,Sci. Total Environ.,2023;Yamaguchi et al.,ACS Appl. Bio Mater.,2025).

Trogocytosis Shapes Immune Responses

The term trogocytosis comes from the ancient Greek Trogo, meaning “to bite”, It refers to a process in which one cell acquires fragments of plasma membrane from a neighboring cell through direct contact.

We are interested in understanding how trogocytosis influences immune responses. So far, we have revealed that MHC trogocytosis play a role in regulating NK cell and CD4 T cell function (Nakayama, Front. Immunol., 2015; Nakamura et al., PNAS, 2013; Nakayama et al., PNAS, 2011). Furthermore, we found that dendritic cells rapidly acquire MHC class I molecules from dead cells to prime CD8 T cells (Hori et al.,iScience 2024).

Trogocytosis is thought to be involved in various immune responses and diseases such as cancer, infection, and autoimmune diseases. However, many aspects of this newly recognized phenomenon remain unknown.