Fetuin-A (FetA) is a free fatty acid transporter and an acute-phase protein that enhances cellular lipid uptake and lipogenesis. In nonruminants, FetA is involved in lipid-induced inflammation. Despite FetA importance in lipid metabolism and inflammation, its expression and dynamics in adipose tissue (AT) of dairy cows are unknown. The objectives of this study were to (1) determine serum and AT FetA dynamics over the periparturient period and in mid-lactation cows in negative energy balance (NEB) after a feed restriction protocol and (2) characterize how an inflammatory challenge affects adipocyte FetA expression. Blood and subcutaneous AT were collected from 16 cows with high (≥3.75, n = 8) or moderate (≤3.5, n = 8) body condition score (BCS) at −26 ± 7 d (far off) and −8 ± 5 d (close up) before calving and at 10 ± 2 d after parturition (early lactation) and from 14 nonpregnant mid-lactation cows (>220 d in milk) after a feed restriction protocol. Serum FetA concentrations were 0.89 ± 0.13 mg/mL at far off, 0.96 ± 0.13 mg/mL at close up, and 0.77 ± 0.13 mg/mL at early lactation and were 1.09 ± 0.09 and 1.17 ± 0.09 mg/mL in feed-restricted and control cows, respectively. Serum and AT FetA contents decreased at the onset of lactation when lipolysis was higher. No changes in AT and serum FetA were observed after feed restriction induced NEB in mid-lactation cows. Prepartum BCS had no effect on serum FetA, but AT expression of AHSG, the gene encoding FetA, was reduced in periparturient cows with high BCS at dry-off throughout all time points. Circulating FetA was positively associated with serum albumin and calcium and with BCS variation over the periparturient period. The dynamics of AHSG expression were analogous to the patterns of lipogenic markers ABDH5, ELOVL6, FABP4, FASN, PPARγ, and SCD1. Expression of AHSG and FetA protein in AT was inversely correlated with AT proinflammatory markers CD68, CD44, SPP1, and CCL2. In vitro, bovine adipocytes challenged with lipopolysaccharide downregulated FetA protein expression. Adipocytes treated with FetA had lower CCL2 expression compared with those exposed to lipopolysaccharide. Overall, FetA is a systemic and local AT negative acute-phase protein linked to AT function in periparturient cows. Furthermore, FetA may support physiological adaptations to NEB in periparturient cows.

Fetuin-A（FetA）是一种游离脂肪酸转运蛋白，是一种急性期蛋白，可增强细胞脂质的摄取和脂肪生成。在非反刍动物中，FetA参与脂质诱导的炎症。尽管FetA在脂质代谢和炎症中很重要，但其在奶牛脂肪组织（AT）中的表达和动态尚不清楚。这项研究的目的是（1）在进食限制方案后确定围产期和泌乳中期处于负能量平衡（NEB）的母牛的血清和AT FetA动态，以及（2）表征炎症挑战如何影响脂肪细胞FetA表达。从16头高（≥3.75，n = 8）或中（≤3.5，n = 8）产犊前-26±7 d（较远）和-8±5 d（近距）和分娩后10±2 d（早期泌乳）以及14个未怀孕中期的身体状况评分（BCS）。限制饲喂后的泌乳母牛（> 220 d牛奶）。远处时的血清FetA浓度为0.89±0.13 mg / mL，近距离时为0.96±0.13 mg / mL，哺乳初期为0.77±0.13 mg / mL，进食限制时为1.09±0.09和1.17±0.09 mg / mL和对照牛。当脂解作用较高时，血清和AT FetA含量在哺乳期开始下降。饲喂限制诱导的NEB在泌乳中期的母牛中未观察到AT和血清FetA的变化。产前BCS对血清FetA无影响，但AT表达 远处时的血清FetA浓度为0.89±0.13 mg / mL，近距离时为0.96±0.13 mg / mL，哺乳初期为0.77±0.13 mg / mL，进食限制时为1.09±0.09和1.17±0.09 mg / mL和对照牛。当脂解作用较高时，血清和AT FetA含量在哺乳期开始下降。饲喂限制诱导的NEB在泌乳中期的母牛中未观察到AT和血清FetA的变化。产前BCS对血清FetA无影响，但AT表达 远处时的血清FetA浓度为0.89±0.13 mg / mL，近距离时为0.96±0.13 mg / mL，早期哺乳期为0.77±0.13 mg / mL，进食限制时为1.09±0.09和1.17±0.09 mg / mL和对照牛。当脂解作用较高时，血清和AT FetA含量在哺乳期开始下降。饲喂限制诱导的NEB在泌乳中期的母牛中未观察到AT和血清FetA的变化。产前BCS对血清FetA无影响，但AT表达 饲喂限制诱导的NEB在泌乳中期的母牛中未观察到AT和血清FetA的变化。产前BCS对血清FetA无影响，但AT表达 饲喂限制诱导的NEB在泌乳中期的母牛中未观察到AT和血清FetA的变化。产前BCS对血清FetA无影响，但AT表达在所有时间点，在干奶期间BCS高的围产期母牛中，编码FetA的基因AHSG降低。围产期，循环中的FetA与血清白蛋白，钙和BCS呈正相关。AHSG表达的动力学类似于脂肪生成标记ABDH5，ELOVL6，FABP4，FASN，PPARγ和SCD1的模式。AT中AHSG和FetA蛋白的表达与AT促炎标记CD68，CD44，SPP1和CCL2呈负相关。在体外，用脂多糖激发的牛脂肪细胞下调了FetA蛋白的表达。FetA处理的脂肪细胞的CCL2较低表达与暴露于脂多糖的那些相比。总体而言，FetA是与围产期母牛的AT功能相关的全身性和局部AT阴性急性期蛋白。此外，FetA可能支持围产期母牛对NEB的生理适应。