Eosinophils from Physiology to Disease: A Comprehensive Review

Figure 1

Eosinophil dynamics. Eosinophil differentiate in the bone marrow under stimulation by IL3, GM-CSF, and IL5, which bind to receptors sharing a common beta chain. Either the beta chain or the specific partner chains of these receptors constitute potential targets for pharmacological modulation. IL5 is crucial for the last stage of eosinophil maturation in the bone marrow as well as for eosinophil release in the circulating blood and subsequent survival. An array of chemokines targeting the chemokine receptor CCR3 promote eosinophil recruitment into organs and tissues. A first set of target tissues hosts a population of regulatory eosinophils involved in the maintenance of the immune homeostasis (a) or of organ functional integrity (b). Other tissues (such as the heart, the gut including the oesophagus, the respiratory tract, the skin, the liver, and bile ducts as well as central or peripheral nerves) are instead targets for eosinophil infiltration during inflammation (c). Eosinophils also promote intravascular inflammation and are able to trigger the coagulation cascade.