Adipose tissue depots of Holstein cows are immune responsive: inflammatory gene expression in vitro

Cytokine production by bovine adipose tissue stromal vascular fraction cells upon Neospora caninum stimulation

In bovines few studies addressed the contribution of adipose tissue to the host immune response to infection. Here we evaluated the in vitro response of bovine adipose tissue stromal vascular fraction (SVF) cells to the protozoan parasite Neospora caninum, using live and freeze-killed tachyzoites. Live N. caninum induced the production of IL-6, IL-1β and IL-10 by SVF cells isolated from subcutaneous adipose tissue (SAT), while in mesenteric adipose tissue (MAT) SVF cell cultures only IL-1β and IL-10 production was increased, showing slight distinct responses between adipose tissue depots. Whereas a clear IL-8 increase was detected in peripheral blood leucocytes (PBL) culture supernatants in response to live N. caninum, no such increase was observed in SAT or MAT SVF cell cultures. Nevertheless, in response to LPS, increased IL-8 levels were detected in all cell cultures. IL-10 levels were always increased in response to stimulation (live, freeze-killed N. caninum and LPS). Overall, our results show that bovine adipose tissue SVF cells produce cytokines in response to N. caninum and can therefore be putative contributors to the host immune response against this parasite.

Endotoxin-induced alterations of adipose tissue function: a pathway to bovine metabolic stress

During the periparturient period, dairy cows exhibit negative energy balance due to limited appetite and increased energy requirements for lactogenesis. The delicate equilibrium between energy availability and expenditure puts cows in a state of metabolic stress characterized by excessive lipolysis in white adipose tissues (AT), increased production of reactive oxygen species, and immune cell dysfunction. Metabolic stress, especially in AT, increases the risk for metabolic and inflammatory diseases. Around parturition, cows are also susceptible to endotoxemia. Bacterial-derived toxins cause endotoxemia by promoting inflammatory processes and immune cell infiltration in different organs and systems while impacting metabolic function by altering lipolysis, mitochondrial activity, and insulin sensitivity. In dairy cows, endotoxins enter the bloodstream after overcoming the defense mechanisms of the epithelial barriers, particularly during common periparturient conditions such as mastitis, metritis, and pneumonia, or after abrupt changes in the gut microbiome. In the bovine AT, endotoxins induce a pro-inflammatory response and stimulate lipolysis in AT, leading to the release of free fatty acids into the bloodstream. When excessive and protracted, endotoxin-induced lipolysis can impair adipocyte's insulin signaling pathways and lipid synthesis. Endotoxin exposure can also induce oxidative stress in AT through the production of reactive oxygen species by inflammatory cells and other cellular components. This review provides insights into endotoxins' impact on AT function, highlighting the gaps in our knowledge of the mechanisms underlying AT dysfunction, its connection with periparturient cows' disease risk, and the need to develop effective interventions to prevent and treat endotoxemia-related inflammatory conditions in dairy cattle.

The Complex Interplay of Insulin Resistance and Metabolic Inflammation in Transition Dairy Cows

During the transition period, dairy cows exhibit heightened energy requirements to sustain fetal growth and lactogenesis. The mammary gland and the growing fetus increase their demand for glucose, leading to the mobilization of lipids to support the function of tissues that can use fatty acids as energy substrates. These physiological adaptations lead to negative energy balance, metabolic inflammation, and transient insulin resistance (IR), processes that are part of the normal homeorhetic adaptations related to parturition and subsequent lactation. Insulin resistance is characterized by a reduced biological response of insulin-sensitive tissues to normal physiological concentrations of insulin. Metabolic inflammation is characterized by a chronic, low-level inflammatory state that is strongly associated with metabolic disorders. The relationship between IR and metabolic inflammation in transitioning cows is intricate and mutually influential. On one hand, IR may play a role in the initiation of metabolic inflammation by promoting lipolysis in adipose tissue and increasing the release of free fatty acids. Metabolic inflammation, conversely, triggers inflammatory signaling pathways by pro-inflammatory cytokines, thereby leading to impaired insulin signaling. The interaction of these factors results in a harmful cycle in which IR and metabolic inflammation mutually reinforce each other. This article offers a comprehensive review of recent advancements in the research on IR, metabolic inflammation, and their intricate interrelationship. The text delves into multiple facets of physiological regulation, pathogenesis, and their consequent impacts.

Acute phase reaction to lipopolysaccharide-induced mastitis in early lactation dairy cows fed nitrogenic, glucogenic, or lipogenic diets

The availability of certain macronutrients is likely to influence the capacity of the immune system. Therefore, we investigated the acute phase response to intramammary (i.mam.) lipopolysaccharide (LPS) in dairy cows fed a nitrogenic diet (n = 10) high in crude protein, a glucogenic diet (n = 11) high in carbohydrates and glucogenic precursors, or a lipogenic diet (n = 11) high in lipids. Thirty-two dairy cows were fed one of the dietary concentrates directly after calving until the end of trial at 27 ± 3 days in milk (mean ± standard deviation). In wk 3 of lactation, 20 µg of LPS was i.mam. injected in one quarter, and sterile NaCl (0.9%) in the contralateral quarter. Milk samples of the LPS-challenged and control quarter were taken hourly from before (0 h) until 9 h after LPS challenge and analyzed for milk amyloid A (MAA), haptoglobin (HP), and IL-8. In addition, blood samples were taken in the morning, and composite milk samples at morning and evening milkings, from 1 d before until 3 d after LPS challenge, and again on d 9, to determine serum amyloid A (SAA) and HP in blood, and MAA and HP in milk. The mRNA abundance of various immunological and metabolic factors in blood leukocytes was quantified by quantitative reverse-transcription PCR from samples taken at -18, -1, 6, 9, and 23 h relative to LPS application. The dietary concentrates did not affect any of the parameters in blood, milk, and leukocytes. The IL-8 was increased from 2 h, HP from 2 to 3 h, and MAA from 6 h relative to the LPS administration in the milk of the challenged quarter and remained elevated until 9 h. The MAA and HP were also increased at 9 h after LPS challenge in whole-udder composite milk, whereas HP and SAA in blood were increased only after 23 h. All 4 parameters were decreased again on d 9. Similar for all groups, the mRNA abundance of HP and the heat shock protein family A increased after the LPS challenge, whereas the mRNA expression of the tumor necrosis factor α and the leukocyte integrin β 2 subunit (CD18) were decreased at 6 h after LPS challenge. The glucose transporter (GLUT)1 mRNA abundance decreased after LPS, whereas that of the GLUT3 increased, and that of the GLUT4 was not detectable. The mRNA abundance of GAPDH was increased at 9 h after LPS and remained elevated. The acute phase protein response was detected earlier in milk compared with blood indicating mammary production. However, immunological responses to LPS were not affected by the availability of specific macronutrients provided by the different diets.

Scientific characterization methods for better utilization of cattle dung and urine: a concise review

Cattle are usually raised for food, manure, leather, therapeutic, and draught purposes. Biowastes from cattle, such as dung and urine, harbor a diverse group of crucial compounds, metabolites/chemicals, and microorganisms that may benefit humans for agriculture, nutrition, therapeutics, industrial, and other utility products. Several bioactive compounds have been identified in cattle dung and urine, which possess unique properties and may vary based on agro-climatic zones and feeding practices. Therefore, cattle dung and urine have great significance, and a balanced nutritional diet may be a key to improved quality of these products/by-products. This review primarily focuses on the scientific aspects of biochemical and microbial characterization of cattle biowastes. Various methods including genomics for analyzing cattle dung and gas chromatography-mass spectroscopy for cattle urine have been reviewed. The presented information might open doors for the further characterization of cattle resources for heterogeneous applications in the production of utility items and addressing research gaps. Methods for cattle's dung and urine characterization.

Tumor necrosis factor-α reduces adiponectin production by decreasing transcriptional activity of peroxisome proliferator-activated receptor-γ in calf adipocytes

Adiponectin (encoded by ADIPOQ) is an adipokine that orchestrates energy homeostasis by modulating glucose and fatty acid metabolism in peripheral tissues. During the periparturient period, dairy cows often develop adipose tissue inflammation and decreased plasma adiponectin levels. Proinflammatory cytokine tumor necrosis factor-α (TNF-α) plays a pivotal role in regulating the endocrine functions of adipocytes, but whether it affects adiponectin production in calf adipocytes remains obscure. Thus, the present study aimed to determine whether TNF-α could affect adiponectin production in calf adipocytes and to identify the underlying mechanism. Adipocytes isolated from Holstein calves were differentiated and used for (1) BODIPY493/503 staining; (2) treatment with 0.1 ng/mL TNF-α for different times (0, 8, 16, 24, or 48 h); (3) transfection with peroxisome proliferator-activated receptor-γ (PPARG) small interfering RNA for 48 h followed by treatment with or without 0.1 ng/mL TNF-α for 24 h; and (4) overexpression of PPARG for 48 h followed by treatment with or without 0.1 ng/mL TNF-α for 24 h. After differentiation, obvious lipid droplets and secretion of adiponectin were observed in adipocytes. Treatment with TNF-α did not alter mRNA abundance of ADIPOQ but reduced the total and high molecular weight (HMW) adiponectin content in the supernatant of adipocytes. Quantification of mRNA abundance of endoplasmic reticulum (ER)/Golgi resident chaperones involved in adiponectin assembly revealed that ER protein 44 (ERP44), ER oxidoreductase 1α (ERO1A), and disulfide bond-forming oxidoreductase A-like protein (GSTK1) were downregulated in TNF-α-treated adipocytes, while 78-kDa glucose-regulated protein and Golgi-localizing γ-adaptin ear homology domain ARF binding protein-1 were unaltered. Moreover, TNF-α diminished nuclear translocation of PPARγ and downregulated mRNA abundance of PPARG and its downstream target gene fatty acid synthase, suggesting that TNF-α suppressed the transcriptional activity of PPARγ. In the absence of TNF-α, overexpression of PPARG enhanced the total and HMW adiponectin content in supernatant and upregulated the mRNA abundance of ADIPOQ, ERP44, ERO1A, and GSTK1 in adipocytes. However, knockdown of PPARG reduced the total and HMW adiponectin content in supernatant and downregulated the mRNA abundance of ADIPOQ, ERP44, ERO1A, and GSTK1 in adipocytes. In the presence of TNF-α, overexpression of PPARG decreased, while knockdown of PPARG further exacerbated TNF-α-induced reductions in total and HMW adiponectin secretion and gene expression of ERP44, ERO1A, and GSTK1. Overall, TNF-α reduces adiponectin assembly in the calf adipocyte, which may be partly mediated by attenuation of PPARγ transcriptional activity. Thus, locally elevated levels of TNF-α in adipose tissue may be one reason for the decrease in circulating adiponectin in periparturient dairy cows.

Effects of Late Gestation Supplements Differing in Fatty Acid Amount and Profile to Beef Cows on Cow Performance, Steer Progeny Growth Performance through Weaning, and Relative mRNA Expression of Genes Associated with Muscle and Adipose Tissue Development

Strategic supplementation during late gestation has the potential to alter progeny performance. Mature fall-calving Simmental × Angus cows were used to evaluate the effects of late gestation supplementation of fatty acids to beef cows on cow performance, steer progeny growth performance during pre-weaning and backgrounding periods, and relative mRNA expression of genes associated with myogenesis and adipogenesis. Cows (n = 190; 4 pasture groups of cows/treatment) grazed endophyte-infected tall fescue and were supplemented during late gestation with calcium salts of either saturated fatty acid/monounsaturated fatty acid (SFA/MUFA), polyunsaturated fatty acid (PUFA), or an isocaloric and isonitrogenous control (CON). There were no differences (p ≥ 0.11) in cow body weight (BW) or body condition scores from pre-supplementation to weaning or steer BW at birth, weaning, or at the end of the backgrounding period. Concentrations of C18:2n-6 in plasma were greater (p = 0.01) in SFA/MUFA and PUFA cows compared to CON cows during supplementation. For mRNA expression in the longissimus muscle of steer progeny from birth to weaning: PAX7 decreased to a greater (p < 0.01) extent for SFA/MUFA and PUFA steers; AGPAT1 and CPT1 increased to a greater (p ≤ 0.02) extent for CON steers. The expression of MYH7 mRNA during the pre-weaning period was greater (p = 0.01) in PUFA. In conclusion, late gestation fatty acid supplementation modified plasma relative concentrations of fatty acids for dams and progeny and modified mRNA expression of genes related to myogenesis and adipogenesis but had limited effects on progeny growth performance during pre-weaning and backgrounding periods.

Tumor necrosis factor-α promotes lipolysis and reduces insulin sensitivity by activating nuclear factor kappa B and c-Jun N-terminal kinase in primary bovine adipocytes

Sustained lipolysis and insulin resistance increase the risk of metabolic dysfunction in dairy cows during the transition period. Proinflammatory cytokines are key regulators of adipose tissue metabolism in nonruminants, but biological functions of these molecules in ruminants are not well known. Thus, the objective of this study was to investigate whether tumor necrosis factor-α (TNF-α) could affect insulin sensitivity and lipolysis in bovine adipocytes as well as the underlying mechanisms. Bovine adipocytes (obtained from the omental and mesenteric adipose depots) isolated from 5 Holstein female calves (1 d old) with similar body weight (median: 36.9 kg, range: 35.5-41.2 kg) were differentiated and used for (1) treatment with different concentrations of TNF-α (0, 0.1, 1, or 10 ng/mL) for 12 h; (2) pretreatment with 10 μM lipolytic agonist isoproterenol (ISO) for 3 h, followed by treatment with or without 10 ng/mL TNF-α for 12 h; and (3) pretreatment with the c-Jun N-terminal kinase (JNK) inhibitor SP600125 (20 μM for 2 h) and nuclear factor kappa B (NF-κB) inhibitor BAY 11-7082 (10 μM for 1 h) followed by treatment with or without 10 ng/mL TNF-α for 12 h. The TNF-α increased glycerol content in supernatant, decreased triglyceride content and insulin-stimulated phosphorylation of protein kinase B suggesting activation of lipolysis and impairment of insulin sensitivity. The TNF-α reduced cell viability, upregulated mRNA abundance of Caspase 3 (CASP3), an apoptosis marker, and increased activity of Caspase 3. In addition, increased phosphorylation of NF-κB and JNK, upregulation of mRNA abundance of interleukin-6 (IL-6), TNFA, and suppressor of cytokine signaling 3 (SOCS3) suggested that TNF-α activated NF-κB and JNK signaling pathways. Furthermore, ISO plus TNF-α-activated NF-κB and JNK signaling pathway to a greater extent than TNF-α alone. Combining TNF-α and ISO aggravated TNF-α-induced apoptosis, insulin insensitivity and lipolysis. In the absence of TNF-α, inhibition of NF-κB and JNK did not alter glycerol content in supernatant, triglyceride content or insulin-stimulated phosphorylation of protein kinase B. In the presence of TNF-α, inhibition of NF-κB and JNK alleviated TNF-α-induced apoptosis, insulin insensitivity and lipolysis. Overall, TNF-α impairs insulin sensitivity and induces lipolysis and apoptosis in bovine adipocytes, which may be partly mediated by activation of NF-κB and JNK. Thus, the data suggested that NF-κB and JNK are potential therapeutic targets for alleviating lipolysis dysregulation and insulin resistance in adipocytes.

Insulin signaling and antioxidant proteins in adipose tissue explants from dairy cows challenged with hydrogen peroxide are altered by supplementation of arginine or arginine plus methionine

Arginine (Arg) and methionine (Met) can elicit anti-inflammatory and antioxidant effects in animals. Unlike Met, however, it is unknown if the supply of Arg can impact key aspects of adipose tissue (AT) function in dairy cows. Since Met and Arg metabolism are linked through the synthesis of polyamines, it is also possible that they have a complementary effect on aspects of AT function during a stress challenge. In this experiment, subcutaneous AT was harvested from four lactating multiparous Holstein cows (~27.0 kg milk per day, body condition score 3.38 ± 0.23) and used for incubations (4 h) with the following: control medium with an "ideal" profile of essential amino acids (IPAA; CTR; Lys:Met 2.9:1), IPAA plus 100 μM H2O2 (HP), H2O2 plus greater Arg supply (HPARG; Lys:Arg 1:1), or H2O2 plus greater Arg and methionine (Met) supply (HPARGMET; Lys:Met 2.5:1 and Lys:Arg 1:1). Western blotting was used to measure abundance of 18 protein targets associated with insulin and AA signaling, nutrient transport, inflammation, and antioxidant response. Reverse transcription polymerase chain reaction (RT-PCR) was used to assess effects on genes associated with Arg metabolism. Among the protein targets measured, although abundance of phosphorylated (p) AKT serine/threonine kinase (P = 0.05) and p-mechanistic target of rapamycin (P = 0.04) were lowest in HP explants, this effect was attenuated in HPARG and especially HPARGMET compared with CTR. Compared with HP, incubation with HPARG led to upregulation of the AA transporter solute carrier family 1 member 3 (L-glutamate transporter; P = 0.03), the reactive oxygen species detoxification-related enzyme glutathione S-transferase mu 1 (GSTM1; P = 0.03), and fatty acid synthase (P = 0.05). Those effects were accompanied by greater abundance of solute carrier family 2 member 4 (insulin-induced glucose transporter) in explants incubated with HPARG and also HPARGMET (P = 0.04). In addition, compared with other treatments, the peak response in abundance of the intracellular energy sensor 5'-prime-AMP-activated protein kinase was detected with HPARGMET (P = 0.003). There was no effect of Arg or Arg plus Met on the mRNA abundance of genes associated with Arg metabolism (ARG1, NOS2, AMD1, SMS, and SRM). Overall, supplementation of Arg alone or with Met partially alleviated the negative effects induced by H2O2. More systematic studies need to be conducted to explore the function of Arg supply with or without Met on AT function.

Lipopolysaccharide induces lipolysis and insulin resistance in adipose tissue from dairy cows

Intense and protracted adipose tissue (AT) fat mobilization increases the risk of metabolic and inflammatory periparturient diseases in dairy cows. This vulnerability increases when cows have endotoxemia-common during periparturient diseases such as mastitis, metritis, and pneumonia-but the mechanisms are unknown. Fat mobilization intensity is determined by the balance between lipolysis and lipogenesis. Around parturition, the rate of lipolysis surpasses that of lipogenesis, leading to enhanced free fatty acid release into the circulation. We hypothesized that exposure to endotoxin (ET) increases AT lipolysis by activation of classic and inflammatory lipolytic pathways and reduction of insulin sensitivity. In experiment 1, subcutaneous AT (SCAT) explants were collected from periparturient (n = 12) Holstein cows at 11 ± 3.6 d (mean ± SE) before calving, and 6 ± 1 d and 13 ± 1.4 d after parturition. Explants were treated with the endotoxin lipopolysaccharide (LPS; 20 µg/mL; basal = 0 µg/mL) for 3 h. The effect of LPS on lipolysis was assessed in the presence of the β-adrenergic agonist and promoter of lipolysis isoproterenol (ISO; 1 µM; LPS+ISO). In experiment 2, SCAT explants were harvested from 24 nonlactating, nongestating multiparous Holstein dairy cows and exposed to the same treatments as in experiment 1 for 3 and 7 h. The effect of LPS on the antilipolytic responses induced by insulin (INS = 1 µL/L, LPS+INS) was established during ISO stimulation [ISO+INS, LPS+ISO+INS]. The characterization of lipolysis included the quantification of glycerol release and the assessment of markers of lipase activity [adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and phosphorylated HSL Ser563 (pHSL)], and insulin pathway activation (AKT, pAKT) using capillary electrophoresis. Inflammatory gene networks were evaluated by real-time quantitative PCR. In periparturient cows, LPS increased AT lipolysis by 67 ± 12% at 3 h across all time points compared with basal. In nonlactating cows, LPS was an effective lipolytic agent at 3 h and 7 h, increasing glycerol release by 115 ± 18% and 68.7 ± 16%, respectively, relative to basal. In experiment 2, LPS enhanced ATGL activity with minimal HSL activation at 3 h. In contrast, at 7 h, LPS increased HSL phosphorylation (i.e., HSL activity) by 123 ± 11%. The LPS-induced HSL lipolytic activity at 7 h coincided with the activation of the MEK/ERK inflammatory pathway. In experiment 2, INS reduced the lipolytic effect of ISO (ISO+INS: -63 ± 18%) and LPS (LPS+INS: -45.2 ± 18%) at 3 h. However, the antilipolytic effect of INS was lost in the presence of LPS at 7 h (LPS+INS: -16.3 ± 16%) and LPS+ISO+INS at 3 and 7 h (-3.84 ± 23.6% and -21.2 ± 14.6%). Accordingly, LPS reduced pAKT:AKT (0.11 ± 0.07) compared with basal (0.18 ± 0.05) at 7 h. Our results indicated that exposure to LPS activated the classic and inflammatory lipolytic pathways and reduced insulin sensitivity in SCAT. These data provide evidence that during endotoxemia, dairy cows may be more susceptible to lipolysis dysregulation and loss of adipocyte sensitivity to the antilipolytic action of insulin.

Branched-Chain Amino Acid Supplementation Alters the Abundance of Mechanistic Target of Rapamycin and Insulin Signaling Proteins in Subcutaneous Adipose Explants from Lactating Holstein Cows

Simple Summary

Branched-chain amino acids (BCAAs) are import regulators of mechanistic target of rapamycin (mTOR). In humans and rodents, increased circulating BCAA levels are positively associated with changes in protein abundance of insulin and amino acid (AA) signaling pathways in organs such as skeletal muscle and adipose. Unlike aspects of fatty acid metabolism (e.g., lipolysis, lipogenesis), it is unknown if BCAA directly affect subcutaneous adipose tissue (SAT) AA metabolism and insulin signaling. We propose that BCAA availability within SAT could enhance aspects of AA and insulin function by promoting increases in the abundance of key proteins.

Abstract

The objective of this study was to investigate changes in protein abundance of mTOR and insulin signaling pathway components along with amino acid (AA) transporters in bovine s.c. adipose (SAT) explants in response to increased supply of Leu, Ile, or Val. Explants of SAT from four lactating Holstein cows were incubated with high-glucose serum-free DMEM, to which the 10 essential AAs were added to create the following treatments: ideal mix of essential AA (IPAA; Lys:Met 2.9:1; Lys:Thr 1.8:1; Lys:His 2.38:1; Lys:Val 1.23:1; Lys:Ile 1.45:1; Lys:Leu 0.85:1; Lys:Arg 2.08:1) or IPAA supplemented with Ile, Val, or Leu to achieve a Lys:Ile of 1.29:1 (incIle), Lys:Val 1.12:1 (incVal), or Lys:Leu (incLeu) 0.78:1 for 4 h. Compared with IPAA, incLeu or incIle led to greater activation of protein kinase B (AKT; p-AKT/total AKT) and mTOR (p-mTOR/total mTOR). Total EAA in media averaged 7.8 ± 0.06 mmol/L across treatments. Incubation with incLeu, incIle, or incVal led to greater protein abundance of solute carrier family 38 member 1 (SLC38A1), a Gln transporter, and the BCAA catabolism enzyme branched-chain α-keto acid dehydrogenase kinase (BCKDK) compared with IPAA. Activation of eukaryotic elongation factor 2 (eEF2; p-eEF2/total eEF2) was also greater in response to incLeu, incIle, or incVal. Furthermore, compared with incLeu or incIle, incVal supplementation led to greater abundance of SLC38A1 and BCKDK. BCKDK is a rate-limiting enzyme regulating BCAA catabolism via inactivation and phosphorylation of the BCKD complex. Overall, data suggested that enhanced individual supplementation of BCAA activates mTOR and insulin signaling in SAT. Increased AA transport into tissue and lower BCAA catabolism could be part of the mechanism driving these responses. The potential practical applications for enhancing post-ruminal supply of BCAA via feeding in rumen-protected form support in vivo studies to ascertain the role of these AAs on adipose tissue biology.

Effects of local or systemic administration of meloxicam on mammary gland inflammatory responses to lipopolysaccharide-induced mastitis in dairy cows

Nonsteroidal anti-inflammatory drugs (NSAID) are commonly used in combination with antimicrobial mastitis treatments to reduce pain. Little is known about whether meloxicam, an NSAID designed for the preferential inhibition of cyclooxygenase-2 over cyclooxygenase-1, affects the mammary immune response. The objective of this study was to analyze the mammary immune response to intramammary (local) or intravenous (systemic) administration of meloxicam with or without immune activation by lipopolysaccharide (LPS). We challenged 108 quarters of 30 cows with or without a low or high dose of LPS from Escherichia coli (0.1 or 0.2 µg/quarter), with or without meloxicam via intramammary administration (50 mg/quarter) or intravenous injection (0.5 mg/kg of body weight; ~300 mg/cow). Intramammary administration of meloxicam alone did not trigger an acute inflammatory response, verified by unchanged somatic cell count (SCC) and lactate dehydrogenase (LDH), BSA, and IgG concentrations in milk, which are normally augmented during mastitis due to an opening of the blood-milk barrier. Similarly, intramammary meloxicam did not change the mRNA abundance of inflammatory factors in mammary gland tissue. As expected, quarters challenged with either dose of LPS showed increased leukocyte infiltration (SCC); increased LDH, BSA, IgG, Na, and Cl concentrations; and diminished K concentrations in milk. In contrast to our hypothesis, the addition of intramammary or intravenous meloxicam did not reduce these markers of mastitis in milk. Instead, intramammary meloxicam appeared to accelerate the SCC response to LPS, but only at the lower LPS dose. Moreover, the mRNA expression of inflammatory factors in mammary tissue was not modified by the intramammary application of meloxicam compared with the contralateral quarters that were challenged with LPS only. We demonstrated for the first time that intramammary meloxicam at a dose of 50 mg/quarter did not trigger an immune response in the mammary glands of dairy cows. At the doses we used, meloxicam (intramammary or systemic) did not lower inflammatory responses. The intramammary administration of meloxicam seemed to stimulate leukocyte recruitment into the milk in quarters challenged with a low dose of LPS. The integrity of the blood-milk barrier was not protected by meloxicam in LPS-stimulated quarters. This study provides the first indications that meloxicam does not limit the inflammatory response in the mammary gland, although it does not impair the mammary immune system.

Molecular networks of insulin signaling and amino acid metabolism in subcutaneous adipose tissue are altered by body condition in periparturient Holstein cows

Peripartal cows mobilize not only body fat but also body protein to satisfy their energy requirements. The objective of this study was to determine the effect of prepartum BCS on blood biomarkers related to energy and nitrogen metabolism, and mRNA and protein abundance associated with AA metabolism and insulin signaling in subcutaneous adipose tissue (SAT) in peripartal cows. Twenty-two multiparous Holstein cows were retrospectively classified into a high BCS (HBCS; n = 11, BCS ≥ 3.5) or normal BCS (NBCS; n = 11, BCS ≤ 3.17) group at d 28 before expected parturition. Cows were fed the same diet as a total mixed ration before parturition and were fed the same lactation diet postpartum. Blood samples collected at -10, 7, 15, and 30 d relative to parturition were used for analyses of biomarkers associated with energy and nitrogen metabolism. Biopsies of SAT harvested at -15, 7, and 30 d relative to parturition were used for mRNA (real time-PCR) and protein abundance (Western blotting) assays. Data were subjected to ANOVA using the MIXED procedure of SAS (v. 9.4; SAS Institute Inc., Cary, NC), with P ≤ 0.05 being the threshold for significance. Cows in HBCS had greater overall plasma nonesterified fatty acid concentrations, due to marked increases at 7 and 15 d postpartum. This response was similar (BCS × Day effect) to protein abundance of phosphorylated (p) protein kinase B (p-AKT), the insulin-induced glucose transporter (SLC2A4), and the sodium-coupled neutral AA transporter (SLC38A1). Abundance of these proteins was lower at -15 d compared with NBCS cows, and either increased (SLC2A4, SLC38A1) or did not change (p-AKT) at 7 d postpartum in HBCS. Unlike protein abundance, however, overall mRNA abundances of the high-affinity cationic (SLC7A1), proton-coupled (SLC36A1), and sodium-coupled amino acid transporters (SLC38A2) were greater in HBCS than NBCS cows, due to upregulation in the postpartum phase. Those responses were similar to protein abundance of p-mTOR, which increased (BCS × Day effect) at 7 d in HBCS compared with NBCS cows. mRNA abundance of argininosuccinate lyase (ASL) and arginase 1 (ARG1) also was greater overall in HBCS cows. Together, these responses suggested impaired insulin signaling, coupled with greater postpartum AA transport rate and urea cycle activity in SAT of HBCS cows. An in vitro study using adipocyte and macrophage cocultures stimulated with various concentrations of fatty acids could provide some insights into the role of immune cells in modulating adipose tissue immunometabolic status, including insulin resistance and AA metabolism.

Age-Dependent Changes of Adipokine and Cytokine Secretion From Rat Adipose Tissue by Endogenous and Exogenous Toll-Like Receptor Agonists

White adipose tissue but recently also brown adipose tissue have emerged as endocrine organs. Age-associated obesity is accompanied by prolonged and elevated lipopolysaccharide (LPS)-induced sickness symptoms and increased cytokine and adipokine levels in the circulation partially originating from adipose tissue. In the present study, ex vivo fat explants were used to investigate how the exogenous pathogen-associated molecular pattern (PAMP) LPS or the endogenous danger-associated molecular patterns (DAMPs) high mobility group box-1 protein (HMGB1) and biglycan modulate the release of cytokines and adipokines/batokines and, thus, could influence systemic and/or local inflammation. The response of adipose tissue (epididymal, retroperitoneal, subcutaneous, and brown) was compared between young lean and old obese rats (2 vs. 24 months old). LPS induced a strong interleukin (IL)-6 and tumor necrosis factor (TNF) alpha release into the supernatant of all adipose tissue types investigated. HMGB1 (subcutaneous) and biglycan (retroperitoneal) led to an increased release of IL-6 and TNFalpha (HMGB1) and decreased visfatin and adiponectin (biglycan) secretion from epididymal adipose tissue (young rats). Visfatin was also decreased by HMGB1 in retroperitoneal adipose tissue of old rats. We found significantly higher leptin (all fat pads) and adiponectin (subcutaneous) levels in supernatants of adipose tissue from old compared to young rats, whereas visfatin secretion showed the opposite. The expression of the biglycan receptor Toll-like receptor (TLR) 2 as well as the LPS and HMGB1 receptors TLR4 and receptor for advanced glycation end products (RAGE) were reduced with age (TLR4/RAGE) and by stimulation with their ligands (subcutaneous). Overall, we revealed that adipokines/adipose-tissue released cytokines show some modulation of their release caused by mediators of septic (batokines) and sterile inflammation with potential implication for acute and chronic disease. Moreover, aging may increase or decrease the release of fat-derived mediators. These data show that DAMPS and LPS locally modulate cytokine secretion while only DAMPS but not LPS can locally alter adipokine secretion during inflammation.

Stress Response Simulated by Continuous Injection of ACTH Attenuates Lipopolysaccharide-Induced Inflammation in Porcine Adrenal Gland

On modern farms, animals are at high risk of bacterial invasion due to environmental stress factors. The adrenal gland is the terminal organ of the stress response. The crosstalk between adrenal endocrine stress and innate immune response is critical for the maintenance of immune homeostasis during inflammation. Thus, it's important to explore whether stresses play a pivotal role in lipopolysaccharide (LPS)-induced inflammatory response in the porcine adrenal gland. Thirty-days-old Duroc × Landrace × Large White crossbred piglets (12 ± 0.5 kg) were randomly allocated into four groups in a 2 × 2 factorial arrangement of treatments, including ACTH pretreatment (with or without ACTH injection) and LPS challenge (with or without LPS injection). Each group consisted of six male piglets. The results showed that our LPS preparation alone induced mRNA expressions of IL-1β, IL-6, TNF-α, IL-10, COX-2, TLR2, TLR4, and GR (P < 0.05). ACTH pretreatment downregulated the TLR2 mRNA and IL-6 protein level induced by our LPS preparation significantly (P < 0.05) by one-way ANOVA analysis. Treatment with LPS alone extremely significantly decreased ssc-miR-338 levels (P < 0.01). Interaction of ACTH × LPS was significant for cNOS level (P = 0.011) and ssc-miR-338 expression (P = 0.04) by two-way ANOVA analysis. The LPS treatment significantly downregulated cNOS levels (P < 0.01), which was significantly attenuated by ACTH pretreatment (P < 0.05). Lipopolysaccharide alone did not affect ssc-miR-146b expression levels compared to that in the vehicle group. However, ACTH pretreatment in combination with LPS significantly increased this micro-RNA expression (P < 0.05). TLRs 1–10 were all expressed in adrenal tissue. The LPS challenge alone induced remarkable compensatory mitochondrial damages at the ultrastructural level, which was alleviated by ACTH pretreatment. Accordingly, ACTH pretreatment was able to block LPS-induced secretion of local adrenal cortisol (P < 0.05). Taken together, our results demonstrate that ACTH pretreatment seems to attenuate LPS-induced mitochondria damage and inflammation that decreased cNOS activity in the adrenal gland and ultimately returned local adrenal cortisol to basal levels at 6 h post LPS injection.

Review: Following the smoke signals: inflammatory signaling in metabolic homeostasis and homeorhesis in dairy cattle

Inflammatory cascades are a critical component of the immune response to infection or tissue damage, involving an array of signals, including water-soluble metabolites, lipid mediators and several classes of proteins. Early investigation of these signaling pathways focused largely on immune cells and acute disease models. However, more recent findings have highlighted critical roles of both immune cells and inflammatory mediators on tissue remodeling and metabolic homeostasis in healthy animals. In dairy cattle, inflammatory signals in various tissues and in circulation change rapidly and dramatically, starting just prior to and at the onset of lactation. Furthermore, several observations in healthy cows point to homeostatic control of inflammatory tone, which we define as a regulatory process to balance immune tolerance with activation to keep downstream effects under control. Recent evidence suggests that peripartum inflammatory changes influence whole-body nutrient flux of dairy cows over the course of days and months. Inflammatory mediators can suppress appetite, even at levels that do not induce acute responses (e.g. fever), thereby decreasing nutrient availability. On the other hand, inhibition of inflammatory signaling with non-steroidal anti-inflammatory drug (NSAID) treatment suppresses hepatic gluconeogenesis, leading to hypoglycemia in some cases. Over the long term, though, peripartum NSAID treatment substantially increases peak and whole-lactation milk synthesis by multiparous cows. Inflammatory regulation of nutrient flux may provide a homeorhetic mechanism to aid cows in adapting to rapid changes in metabolic demand at the onset of lactation, but excessive systemic inflammation has negative effects on metabolic homeostasis through inhibition of appetite and promotion of immune cell activity. Thus, in this review, we provide perspectives on the overlapping regulation of immune responses and metabolism by inflammatory mediators, which may provide a mechanistic underpinning for links between infectious and metabolic diseases in transition dairy cows. Moreover, we point to novel approaches to the management of this challenging phase of the production cycle.

Prepartum dietary energy intake alters adipose tissue transcriptome profiles during the periparturient period in Holstein dairy cows

Background

The aim of the study was to investigate the effect of energy overfeeding during the dry period on adipose tissue transcriptome profiles during the periparturient period in dairy cows.

Methods

Fourteen primiparous Holstein cows from a larger cohort receiving a higher-energy diet (1.62 Mcal of net energy for lactation/kg of dry matter; 15% crude protein) for ad libitum intake to supply 150% (OVR) or 100% (CTR) of energy requirements from dry off until parturition were used. After calving, all cows received the same lactation diet. Subcutaneous adipose tissue (SAT) biopsies were collected at - 14, 1, and 14 d from parturition (d) and used for transcriptome profiling using a bovine oligonucleotide microarray. Data mining of differentially expressed genes (DEG) between treatments and due to sampling time was performed using the Dynamic Impact Approach (DIA) and Ingenuity Pathway Analysis (IPA).

Results

There was a strong effect of over-feeding energy on DEG with 2434 (False discovery rate-corrected P < 0.05) between OVR and CTR at - 14 d, and only 340 and 538 at 1 and 14 d. The most-impacted and activated pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database that were highlighted by DIA analysis at - 14 d in OVR vs. CTR included 9 associated with carbohydrate metabolism, with 'Pyruvate metabolism', 'Glycolysis/gluconeogenesis', and 'Pentose phosphate pathway' among the most-activated. Not surprisingly, OVR led to marked activation of lipid metabolism (e.g. 'Fatty acid biosynthesis' and 'Glycerolipid metabolism'). Unexpected metabolic pathways that were activated at - 14 d in OVR included several related to metabolism of amino acids (e.g. branched chain) and of cofactors and vitamins (thiamin). Among endocrine and immune system pathways, at - 14 d OVR led to marked activation of 'PPAR signalling' and 'Antigen processing and presentation'. Among key pathways affected over time in OVR, a number were related to translation (e.g. mTOR signaling), endocrine/immune signaling (CXCR4 and IGF1), and lipid metabolism (oxidative phosphorylation) with greater activation in OVR vs. CTR specifically at - 14 d. Although statistical differences for several pathways in OVR vs. CTR nearly disappeared at 1 and 14 vs. - 14 d, despite the well-known catabolic state of adipose depots after calving, the bioinformatics analyses suggested important roles for a number of signaling mechanisms at - 14 vs. 14 than 1 vs. -14 d. This was particularly evident in cows fed to meet predicted energy requirements during the dry period (CTR).

Conclusions

Data underscored a strong activation by overfeeding energy of anabolic processes in the SAT exclusively prepartum. The study confirmed that higher-energy diets prepartum drive a transcriptional cascade of events orchestrated in part by the activation of PPARγ that regulate preadipocyte differentiation and lipid storage in SAT. Novel aspects of SAT biology to energy overfeeding or change in physiologic state also were uncovered, including the role of amino acid metabolism, mTOR signaling, and the immune system.

Meloxicam affects the inflammatory responses of bovine mammary epithelial cells

Nonsteroidal anti-inflammatory drugs are used as supportive therapy with antimicrobial treatments for mastitis in cows to alleviate pain of the inflamed mammary gland. They act mainly by inhibition of cyclooxygenases. Meloxicam (MEL) is a drug designed for cyclooxygenase-2 selectivity, which is upregulated upon inflammation, acting as a key enzyme for the conversion of arachidonic acid to prostaglandins. Although some studies in dairy cows showed positive results in recovery from mastitis when MEL was added to the treatments, direct effects of MEL on the immune system of mastitic cows are unknown. The aim of this study was to investigate effects of MEL on the immune response of bovine mammary epithelial cells (MEC) with or without simultaneous immune stimulation by pathogen-associated molecular patterns of common mastitis pathogens. Mammary epithelial cells from 4 cows were isolated and cultured. To evaluate dose effects of MEL, MEC were challenged with or without 0.2 µg/mL lipopolysaccharide (LPS; serotype O26:B6 from Escherichia coli) with addition of increasing concentrations of MEL (0, 0.25, 0.5, 1.0, 1.5, or 2.0 mg/mL). The addition of MEL prevented the increase of mRNA expression of key inflammatory factors in LPS-challenged MEC in a dose-dependent manner. To investigate the effects of MEL on pathogen-specific immune responses of MEC, treatments included challenges with LPS from E. coli and lipoteichoic acid from Staphylococcus aureus with or without 1.5 mg/mL MEL for 3, 6, and 24 h. Meloxicam prevented the increase of mRNA abundance of key inflammatory mediators in response to LPS and lipoteichoic acid, such as tumor necrosis factor, serum amyloid A, inducible nitric oxide synthase, and the chemokines IL-8 and CXC chemokine ligands 3 and 5. The prostaglandin E₂ synthesis in challenged and nonchallenged cells was reduced by MEL within 24 h. Furthermore, MEL reduced the viability and consequently the total RNA yield of the cells. However, mRNA abundance of apoptosis-related enzymes was not affected by any treatment. Meloxicam had clear dose-dependent effects on the immune response of MEC to pathogen-associated molecular patterns of common mastitis pathogens by preventing increased expression of important factors involved in inflammation. This nonsteroidal anti-inflammatory drug also has detrimental effects on cell viability. How these effects would influence the elimination of pathogens from an infected mammary gland during mastitis therapy with meloxicam needs to be further investigated.

Ultrasonographic measurement of liver, portal vein, hepatic vein and perivisceral adipose tissue in high-yielding dairy cows with fatty liver during the transition period

The aim of the present study was to evaluate the potential for diagnosis of fatty liver by means of ultrasonographic measurement of liver and perivisceral adipose tissue as an alternative to blood indicators of lipomobilization and liver biopsy in periparturient high-yielding dairy cows. Thirty cows were enrolled and divided into two groups. The evaluation of body condition score (BCS), non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHB), liver and perivisceral adipose tissue ultrasonographic measurement and histological liver lipid content (GdL) was performed at 15 ± 5 d prepartum (T0), 10 ± 2 d postpartum (T1), 30 ± 2 d postpartum (T2) and 50 ± 2 d postpartum (T3). Mesenteric fat thickness (the thickness of the perivascular adipose tissue) measured on ultrasound was shown to be an independent determinant of fatty liver. The cut-off of the ultrasonographic evaluation of the liver may be useful as a first and practical approach in identifying fatty liver. In conclusion, a non-invasive and reliable diagnostic method for predicting the risk of fatty liver in high yielding dairy cows has been demonstrated.

Dietary energy level affects adipose depot mass but does not impair in vitro subcutaneous adipose tissue response to short-term insulin and tumor necrosis factor-α challenge in nonlactating, nonpregnant Holstein cows

We assessed effects of overfeeding energy to nonlactating and nonpregnant Holstein cows during a length of time similar to a typical dry period on body lipid storage and the abundance of genes related to insulin signaling, inflammation, and ubiquitination in subcutaneous adipose tissue (SAT) in vitro challenged with insulin and recombinant bovine tumor necrosis factor-α. Fourteen cows were randomly assigned to either a high-energy (OVE; net energy for lactation = 1.60 Mcal/kg of dry matter; n = 7) or control (CON; net energy for lactation = 1.30 Mcal/kg of dry matter; n = 7) diet for 6 wk. Immediately after slaughter, liver, kidneys, and mammary gland were separated and weighed. The adipose tissue mass in the omental, mesenteric, and perirenal depots was dissected and weighed. Subcutaneous adipose tissue was collected from the tail-head region and was used as follows: control, bovine insulin (INS) at 1 µmol/L, tumor necrosis factor-α at 5 ng/mL (TNF), and their combination. Despite a lack of difference in final body condition score, OVE cows had greater energy intake and were heavier than CON cows. Furthermore, overfeeding led to greater mass of mesenteric and perirenal adipose, liver, and mammary gland. Overall, SAT incubated with INS had an upregulation of insulin receptor (INSR), interleukin-10 (IL10), small ubiquitin-like modifier 3 (SUMO3), and ubiquitin conjugating enzyme E2I (UBC9), whereas TNF upregulated peroxisome proliferator-activated receptor gamma (PPARG), diacylglycerol O-acyltransferase 2 (DGAT2), interleukin-6 (IL6), nuclear factor kappa B subunit 1 (NFKB1), small ubiquitin-like modifier 2 (SUMO2), and UBC9. Regardless of in vitro treatment, feeding OVE upregulated PPARG, fatty acid synthase (FASN), and insulin induced gene 1 (INSIG1). Abundance of PPARG was greater in SAT of OVE cows cultured individually with INS and TNF. The interaction between diet and in vitro treatment revealed that sterol regulatory element binding transcription factor 1 (SREBF1) had greater abundance in SAT from the CON group in response to culture with INS, whereas SAT from OVE cows had greater SREBF1 abundance in response to culture with TNF. The mRNA abundance of IL6 and NFKB1 was greater in response to TNF treatment and overall in CON cows. Furthermore, SAT from these cows had greater IL10 abundance when cultured with INS and TNF. Overall, data highlighted that overfeeding energy increases adipose tissue mass in part by stimulating transcription of key genes associated with insulin signaling, adipogenesis, and lipogenesis. Because SAT thickness or mass was not measured, the lack of effect of overfeeding on body condition score limits its use to predict overall body lipid storage. An overt inflammatory response in SAT after a 6-wk period of over-consumption of energy could not be discerned.

Metabolic and Endocrine Role of Adipose Tissue During Lactation

The adipose tissue serves an essential role for survival and reproduction in mammals, especially females. It serves primarily as an energy storage organ and is directly linked to the reproductive success of mammals. In wild animals, adipose tissue function is linked to seasonality of the food supply to support fetal growth and milk production. Adipose tissue depots in ruminants and non-ruminants can secrete many signal molecules (adipokines) that act as hormones and as pro- and anti-inflammatory cytokines. The visceral adipose tissue especially appears to be more endocrinologically active than other adipose depots. The endocrine function is important for the overall long-term regulation of energy metabolism and plays an important role in the adaptation to lactation in many mammalian species, including humans. Furthermore, endocrine signals from adipose tissue depots contribute to fertility modulation, immune function, and inflammatory response. Energy homeostasis is modulated by changes in feed intake, insulin sensitivity, and energy expenditure, processes that can be influenced by adipokines in the brain and in peripheral tissues.

Guanylyl cyclase C and guanylin reduce fat droplet accumulation in cattle mesenteric adipose tissue

Guanylyl cyclase C (GC-C) is a member of a family of enzymes that metabolize GTP to cGMP and was first identified as a receptor for heat-stable enterotoxin. Guanylin (GNY) has since been identified as an endogenous ligand for GC-C in the intestine of several mammalian species. The GNY/GC-C system regulates ion transportation and pH in the mucosa. Recently, it was reported that GC-C and GNY are involved in lipid metabolism in rat mesenteric adipose tissue macrophages. To examine the role of GC-C and GNY in lipid metabolism in cattle, we used a bovine mesenteric adipocyte primary culture system and a coculture system for bovine adipocytes and GNY-/GC-C-expressing macrophages. Fat droplets were observed to accumulate in bovine mesenteric adipocytes cultured alone, whereas few fat droplets accumulated in adipocytes indirectly cocultured with macrophages. We also observed that GC-C was present in bovine mesenteric adipose tissue, and that fat droplet accumulation decreased after in vitro GNY administration. Expressions of mRNAs encoding lipogenic factors decreased significantly in adipocytes after either coculture or GNY administration. These results suggest that the GNY/GC-C system is part of the control system for lipid accumulation in bovine mesenteric adipose tissue.

Far-off and close-up dry matter intake modulate indicators of immunometabolic adaptations to lactation in subcutaneous adipose tissue of pasture-based transition dairy cows

The common practice of increasing dietary energy density during the close-up dry period (last ∼3 wk prepartum) has been recently associated with a higher incidence of metabolic disorders after calving. Despite these reports, over-feeding of metabolizable energy (ME) during the far-off, nonlactating period is a common management policy aimed at achieving optimum calving body condition score (BCS) in pasture-based systems, as cows are generally thinner than total mixed ration cows at the end of lactation. Our hypothesis was that both far-off and close-up overfeeding influence the peripartum adipose tissue changes associated with energy balance and inflammatory state. Sixty mid-lactation, grazing dairy cows of mixed age and breed were randomly allocated to 1 of 2 groups that were managed through late lactation to achieve a low and high BCS (approximately 4.25 and 5.0 on a 10-point scale) at dry-off. The low BCS cows were then overfed ME to ensure that they achieved the same BCS as the higher BCS group by calving. Within each rate of BCS gain treatment, cows were offered 65, 90, or 120% of their pre-calving ME requirements for 3 wk pre-calving in a 2 × 3 factorial arrangement of treatments (i.e., 10 cows/treatment). Subcutaneous adipose tissue was collected via biopsy at -1, 1, and 4 wk relative to parturition. Quantitative PCR was used to measure mRNA and microRNA expression of targets related to adipogenesis and inflammation. Cows overfed in the far-off period had increased expression of miR-143 and miR-378 prepartum (-1 wk) indicating greater adipogenesis, consistent with their rapid gain in BCS following dry-off. Furthermore, the lower postpartum expression of IL6, TNF, TLR4, TLR9, and miR-145, and a higher abundance of miR-99a indicated lower body fat mobilization in early lactation in the same group. In the close-up period, feeding either 65 or 120% of ME requirements caused changes in FASN, IL1B, IL6R, TLR9, and the microRNA miR-143, miR-155, and miR-378. Their respective expression patterns indicate a tentative negative-feedback mechanism in metabolically compromised, feed-restricted cows, and a possible immune-related stimulation of lipolysis in apparently static adipocytes in overfed cows. Data from cows fed 90% of ME requirements indicate the existence of a balance between lipolytic (inflammatory-related) and anti-lipolytic signals, to prime the mobilization machinery in light of imminent lactation. Overall, results indicate that far-off dry cow nutrition influences peripartum adipose tissue metabolism, with neither strategy negatively affecting the physiological adaptation to lactation. Furthermore, to ensure a favorable transition, cows should be subjected to a small feed restriction in the close-up period, irrespective of far-off nutritional management.

The localization and differential expression of Serum Amyloid A in bovine liver and adipose tissue depots

In this article the localization of the acute phase protein Serum Amyloid A (SAA) in different depots of bovine adipose tissue (AT) and liver is reported. Quantitative (Real Time) PCR was paired to immunohistochemistry after the production of a specific polyclonal antibody. SAA's mRNA was found in all analyzed AT depots included in the present study, the AT located in the withers being the major source of SAA mRNA. A polyclonal antibody was raised against bovine SAA and was used to validate gene expression analyses. Western Blotting confirmed that SAA is present in all the seven adipose tissue depots include in the present experiment. Anti-SAA polyclonal antibody also stained diffusely adipocytes. In liver, intracytoplasmic immunolabeling was observed in hepatocytes. Staining was generally mild and not diffuse: negative hepatocytes were intermixed with positive ones. A positive intracytoplasmic immunostaining was occasionally observed in endothelial cells lining small blood vessels within AT septa and liver parenchyma. Our data confirm that bovine AT may provide an important source of SAA in healthy subjects. It remains to be determined which is the contribution of AT in the serum concentration of SAA.

Adipose depots differ in cellularity, adipokines produced, gene expression, and cell systems

The race to manage the health concerns related to excess fat deposition has spawned a proliferation of clinical and basic research efforts to understand variables including dietary uptake, metabolism, and lipid deposition by adipocytes. A full appreciation of these variables must also include a depot-specific understanding of content and location in order to elucidate mechanisms governing cellular development and regulation of fat deposition. Because adipose tissue depots contain various cell types, differences in the cellularity among and within adipose depots are presently being documented to ascertain functional differences. This has led to the possibility of there being, within any one adipose depot, cellular distinctions that essentially result in adipose depots within depots. The papers comprising this issue will underscore numerous differences in cellularity (development, histogenesis, growth, metabolic function, regulation) of different adipose depots. Such information is useful in deciphering adipose depot involvement both in normal physiology and in pathology. Obesity, diabetes, metabolic syndrome, carcass composition of meat animals, performance of elite athletes, physiology/pathophysiology of aging, and numerous other diseases might be altered with a greater understanding of adipose depots and the cells that comprise them-including stem cells-during initial development and subsequent periods of normal/abnormal growth into senescence. Once thought to be dormant and innocuous, the adipocyte is emerging as a dynamic and influential cell and research will continue to identify complex physiologic regulation of processes involved in adipose depot physiology.

LC-MS/MS analysis of visceral and subcutaneous adipose tissue proteomes in young goats with focus on innate immunity and inflammation related proteins

The endocrine role of adipose tissue and its involvement in several physiological and pathological processes are well recognized. Studies on human, mouse and rat adipose tissues have made clear that subcutaneous and visceral deposits play different roles, which is also reflected by different protein and gene expression patterns. In ruminants, fat tissues play important biological roles not only for animal health, but also for quality and gain in meat and milk production. Yet very few studies have explored the ruminant adipose tissue proteomes. The aim of our study was to compare subcutaneous and visceral adipose tissues of goat, focusing on proteins involved in immune and inflammatory response. A 2-D LC-MS/MS approach followed by cluster analysis shows a clear distinction between subcutaneous and visceral fat tissue proteomes, and qualitative RT-PCR based analysis of 30 potential adipokines further confirmed the individual expression patterns of 26 of these, including 7 whose mRNA expression was observed for the first time in adipose tissues. This study provides a first description of adipose tissue proteomes in goat, and presents observations on novel proteins related to metabolic and inflammatory pathways. The mass spectrometry data have been deposited to the ProteomeXchange Consortium with the data set identifier PXD000564.

BIOLOGICAL SIGNIFICANCE

The proteomic analysis of different subcutaneous and visceral adipose tissue deposits showed tissue specific differences in protein expressions of well known as well as novel adipokines. This highlights the importance of sampling site when studying adipose tissue's metabolic roles. The protein expression characteristics of adipose tissues was evaluated by quantitative RT-PCR, and confirmed that adipose tissues play a central role in controlling inflammation, detoxification and coagulation pathways, as well as regulation of body fat mobilization in dairy animals. These findings are of particular interest in farm animals where health and production traits are important for animal welfare and for economic gains.

Inflammation- and lipid metabolism-related gene network expression in visceral and subcutaneous adipose depots of Holstein cows

This experiment was conducted to determine the effects of energy overfeeding on gene expression in mesenteric (MAT), omental (OAT), and subcutaneous (SAT) adipose tissue (AT) from nonpregnant and nonlactating Holstein cows. Eighteen cows were randomly assigned to either a controlled energy [LE, net energy for lactation (NE(L)) = 1.35 Mcal/kg of dry matter (DM)] or moderate energy-overfed group (HE, NE(L) = 1.62 Mcal/kg of DM) for 8 wk. Cows were then euthanized and subsamples of MAT, OAT, and SAT were harvested for transcript profiling via quantitative PCR of 34 genes involved in lipogenesis, triacylglycerol (TAG) synthesis, lactate signaling, hepatokine signaling, lipolysis, transcription regulation, and inflammation. The interaction of dietary energy and adipose depot was not significant for any gene analyzed except LPL, which indicated a consistent response to diet. Expression of ACACA and FASN was greater in SAT than MAT, whereas expression of SCD and ADFP were greatest in SAT, intermediate in OAT, and lowest in MAT. However, the 2 visceral depots had greater expression of THRSP, ACLY, LPL, FABP4, GPAM, and LPIN1 compared with SAT. The transcription factor SREBF1 was more highly expressed in MAT and SAT than in OAT. The expression of PNPLA2 was greater in visceral AT sites than in SAT, but other lipolysis-related genes were not differentially expressed among AT depots. Visceral AT depots had greater expression of LEP, ADIPOQ, and SAA3 compared with SAT. Moreover, MAT had greater expression than SAT of proinflammatory cytokines (IL1B and IL6), IL6 receptor (IL6R), and chemokines (CCL2 and CCL5). However, TNF expression was greatest in SAT, lowest in OAT, and intermediate in MAT. Overall, results indicated that visceral AT might be more active in uptake of preformed long-chain fatty acids than SAT, whereas de novo fatty acid synthesis could make a greater contribution to the intracellular pool of fatty acids in SAT than in visceral AT. The visceral AT compared with SAT seem to have a greater capacity for expression (and potentially for secretion) of proinflammatory cytokines; thus, excessive accumulation of visceral lipid due to a long-term overfeeding energy may be detrimental to liver function and overall health of dairy cows, particularly during the transition period.

Resistin in dairy cows: plasma concentrations during early lactation, expression and potential role in adipose tissue

Resistin is an adipokine that has been implicated in energy metabolism regulation in rodents but has been little studied in dairy cows. We determined plasma resistin concentrations in early lactation in dairy cows and investigated the levels of resistin mRNA and protein in adipose tissue and the phosphorylation of several components of insulin signaling pathways one week post partum (1 WPP) and at five months of gestation (5 MG). We detected resistin in mature bovine adipocytes and investigated the effect of recombinant bovine resistin on lipolysis in bovine adipose tissue explants. ELISA showed that plasma resistin concentration was low before calving, subsequently increasing and reaching a peak at 1 WPP, decreasing steadily thereafter to reach pre-calving levels at 6 WPP. Plasma resistin concentration was significantly positively correlated with plasma non esterified fatty acid (NEFA) levels and negatively with milk yield, dry matter intake and energy balance between WPP1 to WPP22. We showed, by quantitative RT-PCR and western blotting, that resistin mRNA and protein levels in adipose tissue were higher at WPP1 than at 5 MG. The level of phosphorylation of several early and downstream insulin signaling components (IRβ, IRS-1, IRS-2, Akt, MAPK ERK1/2, P70S6K and S6) in adipose tissue was also lower at 1 WPP than at 5 MG. Finally, we showed that recombinant bovine resistin increased the release of glycerol and mRNA levels for ATGL (adipose triglyceride lipase) and HSL (hormone-sensitive lipase) in adipose tissue explants. Overall, resistin levels were high in the plasma and adipose tissue and were positively correlated with NEFA levels after calving. Resistin is expressed in bovine mature adipocytes and promotes lipid mobilization in adipose explants in vitro.

Postpartal subclinical endometritis alters transcriptome profiles in liver and adipose tissue of dairy cows

Transcriptome alterations in liver and adipose tissue of cows with subclinical endometritis (SCE) at 29 d postpartum were evaluated. Bioinformatics analysis was performed using the Dynamic Impact Approach by means of KEGG and DAVID databases. Milk production, blood metabolites (non-esterified fatty acids, magnesium), and disease biomarkers (albumin, aspartate aminotransferase) did not differ greatly between healthy and SCE cows. In liver tissue of cows with SCE, alterations in gene expression revealed an activation of complement and coagulation cascade, steroid hormone biosynthesis, apoptosis, inflammation, oxidative stress, MAPK signaling, and the formation of fibrinogen complex. Bioinformatics analysis also revealed an inhibition of vitamin B3 and B6 metabolism with SCE. In adipose, the most activated pathways by SCE were nicotinate and nicotinamide metabolism, long-chain fatty acid transport, oxidative phosphorylation, inflammation, T cell and B cell receptor signaling, and mTOR signaling. Results indicate that SCE in dairy cattle during early lactation induces molecular alterations in liver and adipose tissue indicative of immune activation and cellular stress.

Insulin resistance in dairy cows

Glucose is the molecule that drives milk production, and insulin plays a pivotal role in the glucose metabolism of dairy cows. The effect of insulin on the glucose metabolism is regulated by the secretion of insulin by the pancreas and the insulin sensitivity of the skeletal muscles, the adipose tissue, and the liver. Insulin resistance may develop as part of physiologic (pregnancy and lactation) and pathologic processes, which may manifest as decreased insulin sensitivity or decreased insulin responsiveness. A good knowledge of the normal physiology of insulin is needed to measure the in vivo insulin resistance of dairy cows.

Technical note: identification of reference genes for gene expression studies in different bovine tissues focusing on different fat depots

Selection of stable reference genes (REF) is important in real-time PCR data normalization. Bovine tissues such as the mammary gland, liver, muscle, and s.c. fat from the tail head have been thoroughly explored for stable REF, whereas fewer reports exist for other fat depots. Therefore, a suitable combination of REF was tested for different tissues of dairy cattle. Holstein dairy heifers (n = 25) were supplemented (100 g/d) with a control fat (n = 15) without conjugated linoleic acids or with rumen-protected conjugated linoleic acids (n = 10) from the day of calving until slaughter at 1, 42, or 105 d postpartum (n = 5, 10, and 10, respectively). Samples from 6 fat depots (omental, mesenterial, retroperitoneal, s.c. tail head, s.c. withers, and s.c. sternum), liver, semitendinosus muscle, and mammary gland were collected. The REF mRNA were quantified and their stability was analyzed using geNorm(plus). The 3 most stable REF in individual fat tissues and muscle were EMD (emerin), POLR2A (RNA polymerase II), and LRP10 (lipoprotein receptor-related protein 10); in mammary gland were MARVELD1 (marvel domain containing 1), EMD, and LRP10; and in liver were HPCAL1 (hippocalcin-like 1), LRP10, and EIF3K (Eukaryotic translation initiation factor 3). The 3 most stable REF in s.c. fat were EMD, LRP10, and EIF3K; in visceral fat were POLR2A, LRP10, and MARVELD1; and for all 6 adipose tissues were LRP10, EIF3K, and MARVELD1. When the mammary gland was added to the 6 adipose depots, at least 5 REF (LRP10, POLR2A, EIF3K, MARVELD1, and HPCAL1) were needed to reach the threshold of 0.15. Addition of liver to the above-mentioned tissues increased the V value. The data improve the comparison of gene expression between different fat depots. In each case, GAPDH had the lowest stability value.

Response of the goat mammary gland to infection with Staphylococcus aureus revealed by gene expression profiling in milk somatic and white blood cells

Background

S. aureus is one of the main pathogens responsible for the intra-mammary infection in dairy ruminants. Although much work has been carried out to understand the complex physiological and cellular events that occur in the mammary gland in response to S. aureus, the protective mechanisms are still poorly understood. The objectives of the present study were to investigate gene expression during the early response of the goat mammary gland to an experimental challenge with S. aureus, in order to better understand the local and systemic response and to compare them in two divergent lines of goat selected for high and low milk somatic cell scores.

Results

No differences in gene expression were found between high and low SCS (Somatic Cells Score) selection lines. Analysing the two groups together, an expression of 300 genes were found to change from T0 before infection, and T4 at 24 hours and T5 at 30 hours following challenge. In blood derived white blood cells 8 genes showed increased expression between T0 and T5 and 1 gene has reduced expression. The genes showing the greatest increase in expression following challenge (5.65 to 3.16 fold change) play an important role in (i) immune and inflammatory response (NFKB1, TNFAIP6, BASP1, IRF1, PLEK, BATF3); (ii) the regulation of innate resistance to pathogens (PTX3); and (iii) the regulation of cell metabolism (CYTH4, SLC2A6, ARG2). The genes with reduced expression (−1.5 to −2.5 fold) included genes involved in (i) lipid metabolism (ABCG2, FASN), (ii) chemokine, cytokine and intracellular signalling (SPPI), and (iii) cell cytoskeleton and extracellular matrix (KRT19).

Conclusions

Analysis of genes with differential expression following infection showed an inverse relationship between immune response and lipid metabolism in the early response of the mammary gland to the S. aureus challenge. PTX3 showed a large change in expression in both milk and blood, and is therefore a candidate for further studies on immune response associated with mastitis.

Nutrition, immune function and health of dairy cattle

The large increase in milk yield and the structural changes in the dairy industry have caused major changes in the housing, feeding and management of the dairy cow. However, while large improvements have occurred in production and efficiency, the disease incidence, based on veterinary records, does not seem to be improved. Earlier reviews have covered critical periods such as the transition period in the cow and its influence on health and immune function, the interplay between the endocrine system and the immune system and nutrition and immune function. Knowledge on these topics is crucial for our understanding of disease risk and our effort to develop health and welfare improving strategies, including proactive management for preventing diseases and reducing the severity of diseases. To build onto this the main purpose of this review will therefore be on the effect of physiological imbalance (PI) on immune function, and to give perspectives for prevention of diseases in the dairy cow through nutrition. To a large extent, the health problems during the periparturient period relate to cows having difficulty in adapting to the nutrient needs for lactation. This may result in PI, a situation where the regulatory mechanisms are insufficient for the animals to function optimally leading to a high risk of a complex of digestive, metabolic and infectious problems. The risk of infectious diseases will be increased if the immune competence is reduced. Nutrition plays a pivotal role in the immune response and the effect of nutrition may be directly through nutrients or indirectly by metabolites, for example, in situations with PI. This review discusses the complex relationships between metabolic status and immune function and how these complex interactions increase the risk of disease during early lactation. A special focus will be placed on the major energetic fuels currently known to be used by immune cells (i.e. glucose, non-esterified fatty acids, beta-hydroxybutyrate and glutamine) and how certain metabolic states, such as degree of negative energy balance and risk of PI, contribute to immunosuppression during the periparturient period. Finally, we will address some issues on disease prevention through nutrition.

Contrasting cellularity and fatty acid composition in fat depots from Alentejana and Barrosã bovine breeds fed high and low forage diets

During the finishing phase of bovines, large amounts of subcutaneous and visceral fats are deposited leading to production inefficiencies with major impact on meat quality. A better understanding of the cellularity features of the main fat depots could provide strategies for adipose tissue manipulation. This study assessed the effect of feeding diets with distinct forage to concentrate ratios on the cellularity of two fat depots of beef cattle and their implications on the fatty acid profile. Thus, two phylogenetically distant Portuguese bovine breeds, Alentejana and Barrosã, were selected. The results did not show differences in subcutaneous fat deposition nor in visceral fat depots partitioning. Plasma adipokines concentration failed to show a consistent relationship with fatness, as leptin remained constant in all experimental groups, whereas interleukin-6 was influenced by breed. Fat depot seems to determine the area and number of adipocytes, with larger adipocytes and a lower number of cells in subcutaneous fat than in mesenteric fat. Neither breed nor diet influenced adipocytes area and number. The contents of total fatty acids, partial sums of fatty acids and conjugated linoleic acid isomeric profile were affected by breed and fat depot. The incorporation of saturated fatty acids (SFA), trans fatty acids, polyunsaturated fatty acids (PUFA) and branched chain fatty acids (BCFA) was higher in mesenteric fat depot, whereas subcutaneous fat depot had greater percentages of monounsaturated fatty acids (MUFA). In addition, SFA and MUFA proportions seem to be breed-related. In spite of the less relevant role of diet, the percentages of PUFA and BCFA were influenced by this factor. Under these experimental conditions, the effect of fat depot on cellularity and fatty acid composition prevails over breed or diet, as reinforced by the principal component analysis.

Functional adaptations of the transcriptome to mastitis-causing pathogens: the mammary gland and beyond

Application of microarrays to the study of intramammary infections in recent years has provided a wealth of fundamental information on the transcriptomics adaptation of tissue/cells to the disease. Due to its heavy toll on productivity and health of the animal, in vivo and in vitro transcriptomics works involving different mastitis-causing pathogens have been conducted on the mammary gland, primarily on livestock species such as cow and sheep, with few studies in non-ruminants. However, the response to an infectious challenge originating in the mammary gland elicits systemic responses in the animal and encompasses tissues such as liver and immune cells in the circulation, with also potential effects on other tissues such as adipose. The susceptibility of the animal to develop mastitis likely is affected by factors beyond the mammary gland, e.g. negative energy balance as it occurs around parturition. Objectives of this review are to discuss the use of systems biology concepts for the holistic study of animal responses to intramammary infection; providing an update of recent work using transcriptomics to study mammary and peripheral tissue (i.e. liver) as well as neutrophils and macrophage responses to mastitis-causing pathogens; discuss the effect of negative energy balance on mastitis predisposition; and analyze the bovine and murine mammary innate-immune responses during lactation and involution using a novel functional analysis approach to uncover potential predisposing factors to mastitis throughout an animal's productive life.