Buffalo liver transcriptome analysis suggests immune tolerance as its key adaptive mechanism during early postpartum negative energy balance.

Females undergo negative energy balance (NEB) during the early postpartum period to meet the lactation demands. The liver, being the key metabolic organ, plays a major role in handling NEB. Dairy animals handling high lactation demands are better models to understand the liver adaptive mechanisms during this phase. Therefore, we analyzed the liver transcriptome of dairy buffaloes during early postpartum. Liver biopsies were performed on three lactating buffaloes on the 15th and the 30th days of early postpartum and three heifers (controls) at the diestrous stage. Paired-end Next Generation Sequencing (NGS) identified 509 significantly differentially expressed genes (SDE) in the liver among the three groups. The SDE with log2 fold change > 3 and the unique SDE revealed the promotion of immune suppression (e.g., TCR), apoptosis (e.g., CCDC103), PGF2α synthesis, fat accumulation (e.g., BGLAP) and liver regeneration (e.g., FGF10) pathways, and the downregulation of antigen presentation (e.g., BOLA-DQA) on the 15th day of lactation. Consistently upregulated genes on the 15th and 30th days of early postpartum indicated the promotion of immune tolerance (e.g., IFITM3), medium and long-chain fatty acids' oxidation (e.g., ACSM3), and lipid accumulation (e.g., INSIG1). However, consistently downregulated genes during early postpartum showed immunosuppression, the downregulation of gluconeogenesis from amino acids (e.g., DDO), and the biosynthesis of taurine (e.g., CSAD) and unsaturated fatty acids (e.g., SCD). Functional annotation and network analyses also indicated the promotion of immune tolerance, fat accumulation and decreased gluconeogenesis from amino acids, and estrogen metabolism on the 15th day of lactation. Overall, the liver showed immune tolerance as an adaptive mechanism during early postpartum of buffaloes.