Ketosis Alters Transcriptional Adaptations of Subcutaneous White Adipose Tissue in Holstein Cows during the Transition Period

SIMPLE SUMMARY: Ketosis in dairy cows is one of the common nutritional metabolic diseases during the perinatal period. We conducted the present subcutaneous white adipose tissue transcriptome-based study to investigate the pathogenesis of ketosis in dairy cows. The transcriptome results showed that the expression of PCK1 and PCK2, key enzymes of the glyceroneogenesis, was simultaneously downregulated post-partum compared to pre-partum, possibly resulting in impaired lipid storage in the adipose tissue of ketotic cows. Integrating the GO enrichment analysis and published gene expression traits, the inflammatory response biological process inhibiting PCK1 and PCK2 expression in adipose tissue may be important in the development of ketosis in dairy cows. The findings of the present study provided important clues for the therapeutic and preventive targets for ketosis. ABSTRACT: Ketosis is a common nutritional, metabolic disease during the perinatal period in dairy cows characterized by elevated blood β-hydroxybutyrate (BHBA). In this study, RNA sequencing (RNA-seq) was performed to investigate adaptive changes in adipose tissue during the perinatal period of dairy cows. Blood and tailhead subcutaneous white adipose tissue (sWAT) were obtained from ketotic cows (Ket = 8, BHBA ≥ 1.4 mmol/L) and non-ketotic cows (Nket = 6, BHBA < 1.4 mmol/L) 21 d pre-partum and 10 d post-partum. Compared with pre-partum, decreased lipid synthesis due to down-regulation of PCK1 may be in a strong association with clinical ketosis. Simultaneously, PCK2 was downregulated in the Ket postnatally compared to its expression prenatally, and the expression of PCK2 was 2.7~4.2 times higher than that of PCK1, implying a more severe lipid storage impairment in the Ket. Moreover, compared to pre-partum, the upregulated differentially expressed genes post-partum in the Ket were enriched in the inflammatory response biological process. The higher expression of TNC (tenascin C) in the post-partum Ket relative to the Nket suggested that the adipose tissue of ketotic cows might also be accompanied by tissue fibrosis. Notably, pre-partum CD209 was higher in the Ket than in the Nket, which might be used as a candidate marker for the pre-partum prediction of ketosis. Combined with published gene expression traits, these results suggested that inflammation leads to a more widespread downregulation of the lipid synthesis gene network in adipose tissue in ketotic cows. Additionally, sWAT in post-partum cows with ketosis might also be accompanied by tissue fibrosis which could make the treatment of ketosis more difficult.