Biomarkers in Exhaled Breath Condensate and Serum of Chronic Obstructive Pulmonary Disease and Non-Small-Cell Lung Cancer

Figure 4

The calgranulins, S100A8, S100A9, and S100A12, are secreted by cells of the myeloid lineage such as neutrophils and monocytes. They bind to TLR4 and RAGE on macrophages and activate the NF-𝜅B signalling pathway which leads to the production of proinflammatory cytokines. The production of proinflammatory cytokines then provides a positive feedback by promoting the recruitment of more neutrophils and monocytes. S100A8 and S100A9 are also chemoattractants for MDSCs. MDSCs which move from bone marrow to peripheral blood cause immune suppression and enhance tumourigenesis by impairing cytotoxic CD8+ T cell and NK cell cytotoxicity.