Functional diversity and tissue-specific regulation of Group 2 innate lymphoid cells in barrier immunity

Group 2 innate lymphoid cells (ILC2s) contribute to the maintenance of tissue homeostasis by promoting tissue repair and regulating immune responses. However, excessive or prolonged activation of ILC2s can induce chronic inflammation and tissue fibrosis, thereby contributing to disease exacerbation and progression. Recent studies have revealed that the mechanisms underlying ILC2 activation and their effector functions vary considerably across different tissues. Therefore, understanding the tissue-specific regulation and function of ILC2s is essential for elucidating their roles in both physiological and pathological contexts. Here, we highlight the distinct functional roles of ILC2s in the stomach, intestine, lung, and skin. We examine the differences in activation cues and key effector cytokines produced by ILC2s, illustrating how these cells adapt to the unique immune environments of each tissue. Furthermore, although ILC2s were once thought to function independently of the microbiota, recent findings suggest that microbial communities may influence their activation and function. We also discuss the emerging roles of ILC2s in various diseases, including allergies, inflammatory disorders, and cancer, emphasizing their dual roles in both host defense and disease exacerbation. Gaining a deeper understanding of the distinct functional roles of ILC2s across different tissues will enhance our insight into their involvement in disease pathogenesis and may open new avenues for targeted therapeutic strategies that modulate ILC2 responses.