Protocol for the removal of bound endotoxin from tau protein produced in Escherichia coli

Tau is a widely studied protein that has implications for the progression of neurodegenerative disease. Here, we present a protocol for removing bound endotoxin from Escherichia coli (E. coli)-derived tau protein and verifying endotoxin removal. We describe steps for Triton X-114 treatment, seeding of HEK-Blue hTLR4 with endotoxin standards, collecting conditioned media, and endotoxin quantification. We then detail procedures for stimulating microglia and detecting cytokine secretion. This protocol is crucial for research studies that utilize tau in cell culture. For complete details on the use and execution of this protocol, please refer to Shultz et al.¹.