Eosinophils as Major Player in Type 2 Inflammation: Autoimmunity and Beyond

Area of Science:

• Immunology
• Cell Biology

Background:

• Eosinophils are differentiated granulocytes with established roles in helminth immunity and allergy.
• Their functions extend to homeostasis, infections, autoimmune disorders, and various cancers.

Purpose of the Study:

• To review the multifaceted roles of eosinophils in health and disease.
• To summarize evidence on eosinophil functions in homeostasis, infections, allergic and autoimmune disorders, and cancers.

Main Methods:

• Comprehensive review of recent experimental evidence.
• Analysis of eosinophil structural and biological features, including chemokines, cytokines, granular contents, and extracellular traps.
• Examination of eosinophil involvement in Th2-driven inflammation and specific disease contexts.

Main Results:

• Eosinophils play critical roles in allergic diseases (atopic dermatitis, asthma) and autoimmune disorders (eosinophilic esophagitis, granulomatosis with polyangiitis).
• They are involved in protection against parasites, fungi, viruses, and bacteria.
• Eosinophil infiltration in solid cancers has variable prognostic implications; in hematologic neoplasms, eosinophilia can stem from cytokine dysregulation or myeloid mutations.

Conclusions:

• Eosinophils exhibit a complex, dual role, balancing host defense with potential tissue damage.
• Their involvement in COVID-19 infection is an area of emerging research.
• Understanding eosinophil functions is crucial for managing a wide spectrum of diseases.