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Effect of over-conditioning on the hepatic global gene expression pattern of dairy cows at the end of pregnancy

ABSTRACT: Over-conditioning is a risk factor for upregulated pre- and postpartum fat mobilization. Therefore, we hypothesized that over-conditioning at the end of pregnancy leads to the accumulation of lipids in the liver and modifications of the hepatic gene expression pattern. The aim of this study was to evaluate the effect of over- versus normal-conditioning on the hepatic transcriptomic profile of dairy cows at the end of pregnancy. Ten dry multiparous Holstein cows were euthanized two weeks before expected calving. Body condition score (BCS) and backfat thickness (BFT) were evaluated, and blood samples for nonesterified fatty acids (NEFA) were taken before euthanasia. After euthanasia, liver biopsy samples were collected for further assessment of total lipids and RNA sequencing. Five cows were classified as normal-conditioned (BCS = 2.5–3.5) and five as over-conditioned (BCS = 3.75–5). Regression models confirmed that normal-conditioned cows had lower BCS [3.17 ± 0.10 (least square mean ± SE)], BFT (1.29 ± 0.29 cm), and serum NEFA (0.16 ± 0.04 mmol/L) in comparison to over-conditioned cows (4.35 ± 0.21, 3.14 ± 0.43 cm, and 0.38 ± 0.07 mmol/L for BCS, BFT, and NEFA, respectively). Total liver lipid percentage tended to be lower in normal- than over-conditioned cows (4.63 ± 0.40% and 6.06 ± 0.44%, respectively). In comparison to the mean liver lipid percentage of the normal and over conditioned cows, one over-conditioned cow had a relatively low (5.21%) and one normal-conditioned cow had a relatively high (6.07%) liver lipid percentage. Differentially expressed genes (DEGs) analysis (edgeR quasi-likelihood method) showed that normal-conditioned presented two upregulated and five downregulated genes in comparison to over-conditioned cows. Linear discriminant analysis effects size revealed 23 DEG between normal- versus over-conditioned cows. Notably, the liver of normal-conditioned cows had upregulated genes associated with liver functionality (albumin, selenoprotein P, and insulin-like growth factor binding protein 1 and 2). On the other hand, over-conditioned cows had upregulated genes associated with the acute phase response (complement C3, hemopexin, and lipopolysaccharide-binding protein). High basal lipolysis in over-conditioned cows at the end of pregnancy increases liver lipid content and alters the hepatic gene expression pattern to a pro-inflammatory state.

ORGANISM(S): Bos taurus

PROVIDER: GSE160502 | GEO | 2020/10/31

REPOSITORIES: GEO

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Project description:A transcriptomic approach was used to evaluate potential interactions between prepartum body condition score (BCS) and feeding management in the weeks before calving on hepatic metabolism during the transition period. Thirty-two mid-lactation grazing dairy cows of mixed age and breed were randomly allocated to one of four treatment groups in a 2 × 2 factorial arrangement: two prepartum BCS categories [4.0 (thin, BCS4) and 5.0 (optimal, BCS5); based on a 10-point scale], and two levels of energy intake during the 3 wk preceding calving (75 and 125% of estimated requirements). Liver samples were obtained at -7, 7, and 28 d relative to parturition and subsequent RNA was hybridized to the Agilent 44K Bovine (V2) Microarray chip. The Dynamic Impact Approach was used for pathway analysis, and Ingenuity Pathway Analysis was used for gene network analysis. The greater number of differentially expressed genes in BCS4 cows in response to prepartum feed allowance indicated that these animals were more responsive to prepartum nutrition management than optimally-conditioned cows. However, independent of prepartum BCS, pathway analysis revealed that prepartal feeding level had a marked effect on carbohydrate, amino acid, lipid, and glycan metabolism. Altered carbohydrate and amino acid metabolism indicated a greater and more prolonged negative energy balance post-calving in BCS5 cows overfed prepartum. This was indicated by opposite effects of pre-calving feeding in in BCS4 compared with BCS5 cows in amino acid, vitamin, and co-factor metabolism. The prepartum feed restriction ameliorated the metabolic adaptation to the new lactation in BCS5 cows, while detrimentally affecting BCS4 cows, which seemed to adapt better when overfed. Moreover, alterations in the glycosaminoglycans synthesis pathway support this idea, indicating better hepatic health status in feed-restricted BCS5 cows and overfed BCS4 animals. IPA network analysis indicated liver damage in feed-restricted thin cows, likely due to metabolic overload. Overall, the data indicate that overfeeding in late-pregnancy should be limited to underconditioned animals, while cow with optimal degree of body condition should be maintained on an energy restricted diet.

Project description:Increased energy demands to support lactation, coupled with lowered feed intake capacity results in negative energy balance (NEB) and is typically characterized by extensive mobilization of body energy reserves in the early postpartum dairy cow. The catabolism of stored lipid leads to an increase in the systemic concentrations of nonesterified fatty acids (NEFA) and -hydroxy butyrate (BHB). Oxidation of NEFA in the liver result in the increased production of reactive oxygen species and the onset of oxidative stress and can lead to disruption of normal metabolism and physiology. The immune system is depressed in the peripartum period and early lactation and dairy cows are therefore more vulnerable to bacterial infections causing mastitis and or endometritis at this time. A bovine Affymetrix oligonucleotide array was used to determine global gene expression in the spleen of dairy cows in the early postpartum period. Spleen tissue was removed post mortem from five severe NEB (SNEB) and five medium NEB (MNEB) cows 15 days postpartum.SNEB increased systemic concentrations of NEFA and BHB, and white blood cell and lymphocyte numbers were decreased in SNEB animals. A total of 545 genes were altered by SNEB. Network analysis using Ingenuity Pathway Analysis revealed that SNEB was associated with NRF2-mediated oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, natural killer cell signaling, p53 signaling, downregulation of IL-15, BCL-2, and IFN- ; upregulation of BAX and CHOP and increased apoptosis with a potential negative impact on innate and adaptive immunity. Multiparous Holstein-Friesian cows (n=24) were blocked 2 weeks prior to expected calving date according to parity, body condition score, and previous lactation yield (average lactation 6477M-BM-1354kg) and randomly allocated to mild (MNEB; n=12) or severe (SNEB; n=12) NEB groups. MNEB cows were fed ad lib grass silage and 8 kg day-1 concentrates and milked once daily; SNEB cows were fed 25 kg day-1 silage and 4kg day-1 concentrate and milked three times daily. Measurements of body condition score and EB were used to select cows which showed extremes in EB from each group (MNEB, n=5; SNEB, n=5). Cows were slaughtered on days 6-7 of the first follicular wave after calving (mean number of days post-partum: MNEB mean 13.6 M-BM-1 0.75, range 11M-bM-^@M-^S15; SNEB mean 14.3 M-BM-1 0.56, range 13M-bM-^@M-^S16), based on daily transrectal ultrasonography.At slaughter the entire spleen was removed and weighed, and samples weighing 1 g were dissected, rinsed in RNase-free phosphate buffer, snap frozen in liquid nitrogen, stored for 4 h in dry ice, and subsequently stored at 80M-BM-0C.

Project description:Metabolic challenges experienced by dairy cows during the transition between pregnancy and lactation (also known as peripartum), are of considerable interest from a nutrigenomic perspective. The mobilization of large amounts of non-esterified fatty acids (NEFA) leads to an increase in NEFA uptake in the liver, the excess of which can cause hepatic accumulation of lipids and ultimately fatty liver. Interestingly, peripartum NEFA activate the peroxisome proliferator-activated receptor (PPAR), a transcriptional regulator with known nutrigenomic properties. The study of PPAR activation in the liver of periparturient dairy cows is thus crucial; however, current in vitro models of the bovine liver are inadequate, and the isolation of primary hepatocytes is prohibitive and error-prone. The objective of the current study was to evaluate the use of precision-cut liver slices (PCLS) from liver biopsies as a model for PPAR activation in periparturient dairy cows. Four cows were enrolled in the experiment, and PCLS from each were prepared prepartum (-10 DIM) and postpartum (+10 DIM) and treated with a variety of PPAR agonists and antagonist. Gene expression was assayed through RT-qPCR and RNAseq, and intracellular triglyceride concentration was measured. PCLS treated with PPARγ agonist rosiglitazone displayed upregulation of canonical PPAR targets ACADVL and LIPC in the postpartum, while a PPARδ agonists increased expression of PPAR target PDK4; no gene expression changes were detected in the prepartum, and triglyceride concentrations were unchanged between treatments. Transcriptome sequencing revealed considerable differences in response to PPAR agonist, mainly related to pathways involved with lipid metabolism and the immune response. Among differentially expressed genes, a subset of 91 genes were identified as novel putative PPAR targets in the bovine liver, by cross-referencing our results with a publicly-available dataset of predicted PPAR target genes, and supplementing our finding with prior literature. Our results provide important insights on the use of PCLS as a model for assaying PPAR activation in the peripartum.

Project description:In dairy cows, administration of high dosages of niacin (NA) was found to cause anti-lipolytic effects, which are mediated by the NA receptor hydroxyl-carboxylic acid receptor 2 (HCAR2) in white adipose tissue (WAT), and thereby to an altered hepatic lipid metabolism. However, almost no attention has been paid to possible direct effects of NA in cattle liver, despite showing that HCAR2 is expressed also in the liver of cattle and is even more abundant than in WAT. Due to this, we hypothesized that feeding of rumen-protected NA to dairy cows influences critical metabolic and/or signaling pathways in the liver through inducing changes in the hepatic transcriptome. In order to identify these pathways, we applied genome-wide transcript profiling in liver biopsies obtained at 1 wk postpartum (p.p.) from dairy cows of a recent study (Zeitz et al., 2018) which were fed a total mixed ration without (control group) or with rumen-protected NA from 21 d before calving until 3 wk p.p. Hepatic transcript profiling revealed that a total of 487 transcripts were differentially expressed [filter criteria fold change (FC) > 1.2 or FC < -1.2 and P < 0.05] in the liver at 1 wk p.p. between cows fed NA and control cows. Substantially more transcripts were down-regulated (n = 338), while only 149 transcripts were up-regulated by NA in the liver of cows. Gene set enrichment analysis (GSEA) for the up-regulated transcripts revealed that the most enriched gene ontology (GO) biological process terms were exclusively related to immune processes, such as leukocyte differentiation, immune system process, leukocyte differentiation, activation of immune response and acute inflammatory response. In line with this, the plasma concentration of the acute phase protein haptoglobin tended to be increased in dairy cows fed rumen-protected NA compared to control cows (P < 0.1). GSEA of the down-regulated transcripts showed that the most enriched biological process terms were related to metabolic processes, such as cellular metabolic process, small molecule metabolic process, lipid catabolic process, organic cyclic compound metabolic process, small molecule biosynthetic process and cellular lipid catabolic process. In conclusion, hepatic transcriptome analysis shows that rumen-protected NA induces genes which are involved mainly in immune processes including acute phase response and stress response in dairy cows at wk 1 p.p. These findings indicate that supplementation of rumen-protected NA to dairy cows in the periparturient period may induce or amplify the systemic inflammation-like condition which is typically observed in the liver of high-yielding dairy cows in the p.p. period.

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Effect of over-conditioning on the hepatic global gene expression pattern of dairy cows at the end of pregnancy

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