Lipopolysaccharide induces a delayed iron-handling transcript pattern in primary bovine macrophages

To characterize the timing and between-cow consistency of iron-handling transcript changes after lipopolysaccharide (LPS) exposure in primary bovine monocyte-derived macrophages.

Macrophages from 5 adult Holstein donor cows were exposed to Escherichia coli LPS or PBS and profiled by RNA sequencing at 30 minutes and 6 hours in a paired design. The LPS-versus-PBS effects were estimated with cow-blocked negative-binomial models. Per-cow direction was examined, and 4 focal transcripts were compared directionally with a separate published cohort of 8 cattle sampled 48 hours after LPS exposure.

A treatment-by-time interaction was detected for 5,461 genes. At 6 hours, transferrin receptor, STEAP3 metalloreductase, and solute carrier 11A2 transcripts increased by 2.61, 1.46, and 2.47 log2 fold, respectively, whereas solute carrier 40A1 decreased by 2.24 log2 fold. All 4 changes had the same direction in each of the 5 cows. The separate cohort showed the same direction for all 4 transcripts (transferrin receptor in 7 of 8 animals; the other genes in 8 of 8); its different protocol precluded kinetic replication.

LPS exposure was associated with a later, cow-consistent pattern of increased iron acquisition-associated transcripts and decreased ferroportin transcript abundance. The study does not establish protein abundance, cellular iron movement, or hepcidin dependence.

These transcript-level measures provide an ex vivo framework for studying variation in bovine macrophage iron-handling responses.