MYD88 and hypersensitivity pneumonitis: In summary, TLR-mediated activation of downstream cascades, including NF-κB, MAPK, and MyD88, orchestrates multicellular crosstalk among macrophages, dendritic cells, fibroblasts, and endothelial cells in both hypersensitivity pneumonitis and silicosis, thereby driving coordinated inflammatory and fibrotic responses.