Protocol for measuring endogenous 24(S),25-epoxycholesterol and inducing innate immune memory in mouse macrophages

Multiple metabolic pathways and metabolites are involved in innate immune memory induction of macrophages; however, protocols for in vitro-trained immunity assays induced by metabolites in mouse macrophages are limited. Here, we present a protocol for measuring endogenous 24(S),25-epoxycholesterol and inducing innate immune memory in mouse macrophages. We describe steps for sample preparation, measurement of 24(S),25-epoxycholesterol, and establishment of an in vitro-trained immunity model. We then detail procedures for assays measuring cytokine concentration and for assay for transposase-accessible chromatin using sequencing (ATAC-seq). For complete details on the use and execution of this protocol, please refer to Liu et al.¹.