When
ketosis occurs, supraphysiological concentrations of
nonesterified fatty acids (
NEFA) display lipotoxicity and are closely related to the occurrence of hepatic
lipid accumulation, oxidative stress and
inflammation, resulting in hepatic damage and exacerbating the progression of
ketosis. However, the mechanism of these lipotoxic effects caused by high concentrations of
NEFA in
ketosis is still unclear. Cluster
antigen 36 (CD36), a
fatty acid transporter, plays a vital role in the development of hepatic pathological injury in nonruminants. Thus, the aim of this study was to investigate whether CD36 plays a role in
NEFA-induced hepatic lipotoxicity in dairy cows with clinical
ketosis. Liver tissue and blood samples were collected from healthy (n = 10) and clinically ketotic (n = 10) cows at 3 to 15 d in milk. In addition, hepatocytes isolated from healthy calves were treated with 0, 0.6, 1.2, or 2.4 mM
NEFA for 12 h; or infected with CD36 expressing adenovirus or CD36 silencing
small interfering RNA for 48 h and then treated with 1.2 mM
NEFA for 12 h. Compared with healthy cows, clinically ketotic cows had greater concentrations of serum
NEFA and β-hydroxybutyrate (BHB) and activities of
aspartate aminotransferase (AST) and
alanine aminotransferase (ALT) but lower serum
glucose. Besides, dairy cows with clinical
ketosis displayed excessive hepatic
lipid accumulation. More importantly, these alterations were accompanied by an increased abundance of hepatic CD36. In the cell culture model, exogenous
NEFA (0, 0.6, 1.2, or 2.4 mM) treatment could dose-dependently increase the abundance of CD36. Meanwhile,
NEFA (1.2 mM) increased the content of
triacylglycerol (TAG),
reactive oxygen species (ROS) and
malondialdehyde (MDA), and decreased the activities of
glutathione peroxidase (GSH-Px) and
superoxide dismutase (SOD). Moreover,
NEFA upregulated phosphorylation levels of nuclear factor κB (NF-κB) and the inhibitor of NF-κB (IκB) α, along with the upregulation of
protein abundance of NLR family pyrin domain containing 3 (NLRP3) and caspase-1, and
mRNA abundance of IL1B,
IL6, and
tumor necrosis factor α (TNFA). These alterations induced by
NEFA in bovine hepatocytes were associated with increased
lipid accumulation, oxidative stress and
inflammation, which could be further aggravated by CD36 overexpression. Conversely, silencing CD36 attenuated these
NEFA-induced detriments. Overall, these data suggest that CD36 may be a potential therapeutic target for
NEFA-induced hepatic
lipid accumulation, oxidative stress, and
inflammation in dairy cows.