IL24, also known as melanoma differentiation-associated gene-7 (MDA-7), is a cytokine belonging to the IL-10 family. It has diverse functions, playing roles in maintaining tissue epithelial layer integrity and homeostasis, and is involved in host defense mechanisms, especially in responses from epithelial cells during infections [1]. It also contributes to the tissue-healing process after injury caused by infection or inflammation.

In mouse models, Il24 ablation impedes epidermal proliferation, re-epithelialization, capillary and fibroblast regeneration within the dermal wound bed, indicating its crucial role in tissue repair [2]. In the context of idiopathic pulmonary fibrosis, IL24 deficiency protects mice from bleomycin-induced lung injury and fibrosis by attenuating TGF-β1 production and reducing M2 macrophage infiltration, suggesting its involvement in promoting pulmonary fibrosis development [3].

In conclusion, IL24 is essential for tissue repair and homeostasis. Gene-knockout mouse models have revealed its roles in tissue repair processes and in disease conditions such as pulmonary fibrosis. Understanding IL24's functions through these models provides insights into potential therapeutic targets for related diseases.

References:

1. Ouyang, Wenjun, Rutz, Sascha, Crellin, Natasha K, Valdez, Patricia A, Hymowitz, Sarah G. . Regulation and functions of the IL-10 family of cytokines in inflammation and disease. In Annual review of immunology, 29, 71-109. doi:10.1146/annurev-immunol-031210-101312. https://pubmed.ncbi.nlm.nih.gov/21166540/

2. Liu, Siqi, Hur, Yun Ha, Cai, Xin, Mucida, Daniel, Fuchs, Elaine. 2023. A tissue injury sensing and repair pathway distinct from host pathogen defense. In Cell, 186, 2127-2143.e22. doi:10.1016/j.cell.2023.03.031. https://pubmed.ncbi.nlm.nih.gov/37098344/

3. Rao, Li-Zong, Wang, Yi, Zhang, Lei, Wang, Cong-Yi, Zhang, Huilan. 2020. IL-24 deficiency protects mice against bleomycin-induced pulmonary fibrosis by repressing IL-4-induced M2 program in macrophages. In Cell death and differentiation, 28, 1270-1283. doi:10.1038/s41418-020-00650-6. https://pubmed.ncbi.nlm.nih.gov/33144678/