TLR4 and mastitis: The following three lines of evidence were used to formulate a hypothesis regarding the potential involvement of piRNAs in the regulation of mastitis in dairy cows through key pathways such as TLR4/NF-κB: First, mastitis and other inflammatory diseases share a similar immune microenvironment, characterized by the infiltration of inflammatory cells such as monocytes, dendritic cells, and macrophages that release reactive oxygen species (ROS) and proteases, thereby exacerbating tissue damage [192].