Gene expression of immunologically important factors in blood cells, milk cells, and mammary tissue of cows

Effect of different dietary regimens at dry-off on performance, metabolism, and immune system in dairy cows

Concentrate withdrawal and feed restriction are commonly used to reduce milk production and to facilitate dry-off, but may impair immune function in dairy cows. We investigated the effect of feed rations providing different amounts of nutrients in combination with feed restriction on performance, endocrine, and metabolic responses, as well as on leukocyte function before and after abrupt dry-off. Forty-three cows were studied from d 12 before until d 6 after dry-off (56 d before scheduled calving). Cows were fed experimental concentrates rich in crude protein (nitrogenic, n = 14), glucogenic precursors (glucogenic, n = 14), or lipids (lipogenic, n = 15). On d 3 before dry-off, total feed allowance was restricted to 50% in half of the animals of each dietary group, whereas feed allowance remained unchanged in the other animals. Performance parameters (milk yield, milk composition, and dry matter intake) were recorded, and daily blood and milk samples were taken and analyzed for various metabolic and endocrine parameters. Additionally, activity and mRNA abundance of several genes in leukocytes were measured at selected time points before and after feed restriction and dry-off, respectively. Feed restriction immediately resulted in a negative energy balance and decreased milk production. Concomitantly, concentrations of nonesterified fatty acids increased, whereas insulin, insulin-like growth factor-1, and glucagon decreased. After dry-off, energy balance turned positive and plasma nonesterified fatty acids decreased. Plasma glucose, insulin, and insulin-like growth factor-1 concentrations increased in all groups after dry-off. Glucose, insulin, and glucagon concentrations in plasma were higher in nonrestricted compared with restricted animals after dry-off. The experimental concentrate types marginally affected the investigated metabolic and endocrine factors, with the exception of elevated milk and plasma urea concentrations in cows fed the nitrogenic concentrate. Chemotactic and phagocytic activity of leukocytes were not affected by diets, feed restriction, or dry-off. Likewise, blood leukocyte mRNA abundance encoding for tumor necrosis factor α (TNF), heat shock protein family A (HSP70), and the glucose transporters (GLUT) 1 and 3 remained unchanged throughout the study period. Overall, the short-term negative energy balance induced by feed restriction was temporarily accompanied by metabolic adaptations, but did not alter the studied factors related to the immune system. Metabolic and endocrine adaptations supporting milk synthesis were continued during the first days after dry-off despite cessation of milking. Thus, the abrupt dry-off resulted in a short-term increase of glucose and triglyceride concentrations, with a delayed endocrine response to re-establish nutrient homeostasis in blood.

The Protective Effects of Lactobacillus plantarum KLDS 1.0344 on LPS-Induced Mastitis In Vitro and In Vivo

Cow mastitis, which significantly lowers milk quality, is mainly caused by pathogenic bacteria such as E. coli. Previous studies have suggested that lactic acid bacteria can have antagonistic effects on pathogenic bacteria that cause mastitis. In the current study, we evaluated the in vitro and in vivo alleviative effects of L. plantarum KLDS 1.0344 in mastitis treatment. In vitro antibacterial experiments were performed using bovine mammary epithelial cell (bMEC), followed by in vivo studies involving mastitis mouse models. In vitro results indicate that lactic acid was the primary substance inhibiting the E. coli pathogen. Meanwhile, treatment with L. plantarum KLDS 1.0344 can reduce cytokines' mRNA expression levels in the inflammatory response of bMEC induced by LPS. In vivo, the use of this strain reduced the secretion of inflammatory factors IL-6, IL-1β, and TNF-α, and decreased the activity of myeloperoxidase (MPO), and inhibited the secretion of p-p65 and p-IκBα. These results indicate that L. plantarum KLDS 1.0344 pretreatment can reduce the expression of inflammatory factors by inhibiting the activation of NF-κB signaling pathway, thus exerting prevent the occurrence of inflammation in vivo. Our findings show that L. plantarum KLDS 1.0344 has excellent properties as an alternative to antibiotics and can be developed into lactic acid bacteria preparation to prevent mastitis disease.

Effects of an oral hydro-ethanolic purple coneflower extract on performance, clinical health and immune parameters in calves

The objective of this randomized, placebo-controlled, double-blinded field trial was to investigate the effects of oral administration of purple coneflower (Echinacea purpurea L. (EP)) on performance, health and immune parameters in calves. Calves (n = 27) were enrolled to three groups (9 calves per group): 0.5 g EP/calf per day (ECL), 5 g EP/calf per day (ECH) or placebo. Calves were vaccinated with Bluetongue-Virus (BTV) serotype 4 vaccine to investigate EPs effects on seroconversion. Clinical and performance parameters, inter alia body weight, health and milk intake were recorded for 57 days. Blood samples were analyzed for BTV antibodies and IgG by ELISA, white and red blood cell counts by flow cytometry and mRNA abundance of various inflammatory markers in leukocytes (IL-1β, IL-8, tumor necrosis factor α (TNFα), cyclooxygenase 2 (Cox-2) and prostaglandin E synthase) was studied. The findings demonstrated no differences between groups regarding performance parameters. In all groups, calves suffered from diarrhea for a minimum of 2 days, but EP reduced the number of diarrhea days by 44% in ECL and increased the body temperature. Interestingly, ECL resulted in an increased number of respiratory disease days during the follow-up period. EP did not change blood cell and IgG counts, whereas eosinophil granulocytes were reduced in ECL. Decreased levels of hemoglobin and hematocrit were found in ECH. Prostaglandin E synthase levels in leukocytes were higher in ECL and ECH, whereas no differences were obtained for IL-1β, IL-8, TNFα and Cox-2. Due to the unexpected occurrence of BTV seropositive calves before the first vaccination, 13 calves were excluded from the evaluation on seroconversion and no statistical analyses could be performed regarding antibody production. BTV-4 antibodies were not produced in 4 placebo-calves, whereas 4 of 5 and 1 of 6 ECL- and ECH-calves produced antibodies. Further investigations are needed to draw final conclusions on mode of action and efficacy of EP in calves.

Expression patterns of major genes in fatty acid synthesis, inflammation, oxidative stress pathways from colostrum to milk in Damascus goats

The molecular regulation of milk secretion and quality in the transition period from colostrum to milk in goats is largely unknown. In the present study, mammary gland secretion of goats was collected in 0th, 4th, 7th, 14th and 28th days after parturition. In addition to composition and fatty acid profile of colostrum or milk, FASN, SCD, ACACA, COX-2, NRF2, TLR2, NF-kB, LTF and PTX3 genes expression patterns were determined from milk somatic cells. While somatic cell count (SCC), malondialdehyde (MDA), fat, fat-free dry matter, protein and lactose were highest as expression levels of the oxidative and inflammatory genes, freezing point and electrical conductivity were lowest in colostrum. With the continuation of lactation, most of the fatty acids, n3 ratio, and odour index increased but C14:0 and C16:0 decreased. While FASN was upregulated almost threefolds in 14th day, ACACA was upregulated more than fivefolds in 7th and 14th days. Separately, the major genes in fatty acid synthesis, inflammation and oxidative stress were significantly associated with each other due to being positively correlated. MDA was positively correlated with SCC and some of the genes related inflammation and oxidative stress. Furthermore, significant negative correlations were determined between SCC and fatty acid synthesis related genes. With this study, transition period of mammary secretion was particularly clarified at the molecular levels in Damascus goats.

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.

Gene expression of the heat stress response in bovine peripheral white blood cells and milk somatic cells in vivo

Heat stress in dairy cattle leads to reduction in feed intake and milk production as well as the induction of many physiological stress responses. The genes implicated in the response to heat stress in vivo are not well characterised. With the aim of identifying such genes, an experiment was conducted to perform differential gene expression in peripheral white blood cells and milk somatic cells in vivo in 6 Holstein Friesian cows in thermoneutral conditions and in 6 Holstein Friesian cows exposed to a short-term moderate heat challenge. RNA sequences from peripheral white blood cells and milk somatic cells were used to quantify full transcriptome gene expression. Genes commonly differentially expressed (DE) in both the peripheral white blood cells and in milk somatic cells were associated with the cellular stress response, apoptosis, oxidative stress and glucose metabolism. Genes DE in peripheral white blood cells of cows exposed to the heat challenge compared to the thermoneutral control were related to inflammation, lipid metabolism, carbohydrate metabolism and the cardiovascular system. Genes DE in milk somatic cells compared to the thermoneutral control were involved in the response to stress, thermoregulation and vasodilation. These findings provide new insights into the cellular adaptations induced during the response to short term moderate heat stress in dairy cattle and identify potential candidate genes (BDKRB1 and SNORA19) for future research.

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.

Immunomodulation of IL-1, IL-6 and IL-8 cytokines by Prosopis juliflora alkaloids during bovine sub-clinical mastitis

The current work is focused on establishing therapeutic protocol using unconventional drugs of herbal origin and studying their mechanism of action at molecular level in the treatment of bovine sub-clinical mastitis. It explores the potential of different cytokines which can be used for diagnosis, prognosis and monitoring of bovine sub-clinical mastitis. Prosopis juliflora alkaloids was administered intramammarily in 24 sub-clinically affected quarters once a day for 5 consecutive days at the rate of 10 ml of 1% formulation. In 18 disease control quarters, sterile normal saline was infused. The bacterial cultural examination, somatic cell count (SCC) and cytokines (IL-1β, IL-6, IL-8, IL-12, GM-CSF, IFN-γ, TNF-α) expression by real-time PCR were evaluated on day 7, 14, 21 and 28 post-last treatment from milk samples. Around 75.0% of treatment group quarters showed significant (p < 0.05) reduction in SCC on day 28 post-last treatment, whereas 94.4% control group quarters did not show any significant decline in SCC. 58.3% of treated quarters showed both bacteriological cure as well as significant (p < 0.05) reduction in SCC on day 28 post-last treatment. While, among control group quarters, 83.3% quarters not only remained bacteriological positive, they also did not show any significant decline in SCC. The in vitro antimicrobial activity of alkaloids of P. juliflora was evaluated. Lower concentrations of alkaloids (0.25% and 0.50%) dissolved in normal saline showed zone of inhibition against 12 out of 15 isolates, however higher concentration (1, 1.5, 2, 2.5 and 5%) showed zone of inhibition against all 15 bacterial isolates. The gene expression level of IL-1β, IL-8 and IFN-γ cytokines exhibited significant difference between healthy and sub-clinically affected quarters highlighting the potential of these cytokines in the diagnosis of bovine sub-clinical mastitis. Down-regulation of IL-1, IL-6, IL-8 and IFN-γ cytokines in treated quarters can be explored for making the prognosis and monitoring post-treatment disease progression of bovine sub-clinical mastitis. The P. juliflora alkaloid demonstrated strong in vitro and in vivo antibacterial activity, along with causing immunomodulation by enhancing post-treatment gene expression of IL-1, IL-6 and IL-8 cytokines. Therefore, P. juliflora alkaloids hold a strong claim as an effective alternative herbal therapy in bovine sub-clinical mastitis.

Effect of the Ketone Body Beta-Hydroxybutyrate on the Innate Defense Capability of Primary Bovine Mammary Epithelial Cells

Negative energy balance and ketosis are thought to cause impaired immune function and to increase the risk of clinical mastitis in dairy cows. The present in vitro study aimed to investigate the effect of elevated levels of the predominant ketone body β-hydroxybutyrate on the innate defense capability of primary bovine mammary epithelial cells (pbMEC) challenged with the mastitis pathogen Escherichia coli (E. coli). Therefore, pbMEC of healthy dairy cows in mid- lactation were isolated from milk and challenged in culture with 3 mM BHBA and E. coli. pbMEC stimulated with E. coli for 6 h or 30 h showed an up-regulation of several innate immune genes, whereas co-stimulation of pbMEC with 3 mM BHBA and E. coli resulted in the down-regulation of CCL2, SAA3, LF and C3 gene expression compared to the challenge with solely the bacterial stimulus. These results indicated that increased BHBA concentrations may be partially responsible for the higher mastitis susceptibility of dairy cows in early lactation. Elevated levels of BHBA in blood and milk during negative energy balance and ketosis are likely to impair innate immune function in the bovine mammary gland by attenuating the expression of a broad range of innate immune genes.

Association of polymorphism within LTF gene promoter with lactoferrin concentration in milk of Holstein cows

This study analyzed the association between single nucleotide polymorphism (A/C) in position -28 located in the TATA box of LTF gene and the lactoferrin concentration in bovine milk secreted by healthy and infected udders. Out of 241, 69 cows were selected into the experimental group and were divided into 3 groups according to mean value of somatic cell count (SCC): I < 180,000 cells/mL, II: 180,000-350,000 cells/mL and III > 350,000 cells/mL. In each SCC group, three LTF genotypes: AA, AC and CC were identified by PCR-SSCP method. A total of 604 milk samples were collected monthly and lactoferrin concentration was measured by ELISA. The 1-way ANOVA within SCC groups was performed to estimate association of -28 A/C genotypes with mean lactoferrin concentration per lactation. In the group of healthy cows (< 180,000 cells/mL) LTF concentration in milk cows with the AA genotype (107.58 ± 17.92 μg/mL) was significantly higher than in homozygotes CC (52.09 ± 19.01 μg/mL). Unexpectedly, in cows with elevated SCC (> 350,000 cells/mL) we observed a significant opposite relationship (207.21 ± 28.50 in CC vs 115.0 ± 28.6 μg/mL in AA). We hypothesized that a promoter with allele C, which cannot be recognized as a TATA sequence is becoming more accessible for other transcription factors, which may induce alternative LTF gene expression. We assume that our results demonstrate a very interesting effect of differential gene expression depending on polymorphism in a key regulatory motif (TATA box) and also on the health status of mammary tissues.

Lactoferrin gene variants, their expression in the udder and mastitis susceptibility in dairy cattle

Lactoferrin gene (LF) is regarded as one of the potential markers of mastitis susceptibility/resistance in dairy cattle. The study’s aim was therefore, to investigate the feasibility of two single nucleotide polymorphisms (SNP), placed in the 5′-flanking region and 3′-untranslated region of the LF gene, to serve as mastitis markers. The associations between these SNP and the expression of LF, both on mRNA and protein level, were estimated in the milk of Polish Holstein-Friesian cows. The relationships between polymorphisms and cows’ estimated breeding values (EBV) for somatic cell count were also calculated. It was shown that both polymorphisms have a significant impact on lactoferrin content in milk, and that LF+32 SNP is associated with the cow’s EBV for somatic cell count. No association between SNP chosen for the study and lactoferrin mRNA abundance in milk somatic cells was observed. We propose LF+32 SNP for a molecular marker of mastitis resistance in dairy cows.

The inflammatory response of primary bovine mammary epithelial cells to Staphylococcus aureus strains is linked to the bacterial phenotype

Staphylococcus aureus is a major mastitis-causing pathogen in dairy cows. The latex agglutination-based Staphaurex test allows bovine S. aureus strains to be grouped into Staphaurex latex agglutination test (SLAT)-negative [SLAT(−)] and SLAT-positive [SLAT(+)] isolates. Virulence and resistance gene profiles within SLAT(−) isolates are highly similar, but differ largely from those of SLAT(+) isolates. Notably, specific genetic changes in important virulence factors were detected in SLAT(−) isolates. Based on the molecular data, it is assumed that SLAT(+) strains are more virulent than SLAT(−) strains. The objective of this study was to investigate if SLAT(−) and SLAT(+) strains can differentially induce an immune response with regard to their adhesive capacity to epithelial cells in the mammary gland and in turn, could play a role in the course of mastitis. Primary bovine mammary epithelial cells (bMEC) were challenged with suspensions of heat inactivated SLAT(+) (n = 3) and SLAT(−) (n = 3) strains isolated from clinical bovine mastitis cases. After 1, 6, and 24 h, cells were harvested and mRNA expression of inflammatory mediators (TNF-α, IL-1β, IL-8, RANTES, SAA, lactoferrin, GM-CSF, COX-2, and TLR-2) was evaluated by reverse transcription and quantitative PCR. Transcription (ΔΔCT) of most measured factors was induced in challenged bMEC for 6 and 24 h. Interestingly, relative mRNA levels were higher (P<0.05) in response to SLAT(+) compared to SLAT(−) strains. In addition, adhesion assays on bMEC also showed significant differences between SLAT(+) and SLAT(−) strains.

The present study clearly shows that these two S. aureus strain types cause a differential immune response of bMEC and exhibit differences in their adhesion capacity in vitro. This could reflect differences in the severity of mastitis that the different strain types may induce.

Lipopolysaccharides, cytokines, and nitric oxide affect secretion of prostaglandins and leukotrienes by bovine mammary gland epithelial cells

The aims of this study were to determine the effects of lipopolysaccharides (LPS), tumor necrosis factor (TNF), interleukin 1 alpha (IL-1α), nitric oxide donor (NONOate), or the combination of TNF + IL-1α + NONOate on the following: (i) secretion of prostaglandin (PG)-F(2α), PGE(2), leukotriene (LT)-B(4), and LTC(4) by epithelial cells of the teat cavity and lactiferous sinus of bovine mammary gland; (ii) messenger RNA (mRNA) transcription of enzymes responsible for arachidonic acid (AA) metabolism (prostaglandin-endoperoxide synthase 2 [PTGS2], prostaglandin E synthase [PTGES], prostaglandin F synthase [PGFS], and arachidonate 5-lipooxygenase [ALOX5]); and (iii) proliferation of the cells. The cells were stimulated for 24 h. Prostaglandins and LT were measured by enzyme immunoassay, mRNA transcription of enzymes was determined by real-time reverse transcription polymerase chain reaction, and the cell viability was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide. All factors increased PG secretion, but the highest stimulation was observed after TNF and IL-1α (P < 0.001). Tumor necrosis factor, NONOate, and TNF + IL-1α + NONOate increased LTB(4) production (P < 0.01), whereas LTC(4) was increased by LPS, TNF, and IL-1α (P < 0.01). Lipopolysaccharides, TNF, IL-1α, and the reagents combination increased PTGS2, PTGES, and PGFS mRNA transcription (P < 0.01), whereas ALOX5 mRNA transcription was increased only by TNF (P < 0.001). Lipopolysaccharides, TNF, IL-1α, NONOate, and the combination of reagents increased the cell number (P < 0.001). Mediators of acute-clinical Escherichia coli mastitis locally modulate PG and LT secretion by the epithelial cells of the teat cavity and lactiferous sinus, which might be a useful first line of defense for the bovine mammary gland. Moreover, the modulation of PG and LT secretion and the changing ratio of luteotropic (PGE(2), LTB(4)) to luteolytic (PGF(2α), LTC(4)) metabolites may contribute to disorders in reproductive functions.

Selection of suitable reference genes for quantitative gene expression studies in milk somatic cells of lactating cows (Bos indicus)

We assessed the suitability of 9 internal control genes (ICG) in milk somatic cells of lactating cows to find suitable reference genes for use in quantitative PCR (qPCR). Eighteen multiparous lactating Sahiwal cows were used, 6 in each of 3 lactation stages: early (25 ± 5 d in milk), mid (160 ± 15 d in milk), and late (275 ± 25 d in milk) lactation. Nine candidate reference genes [glyceraldehyde 3-phosphate dehydrogenase (GAPDH), protein phosphatase 1 regulatory subunit 11 (PPP1R11), β-actin (ACTB), β-2 microglobulin (B2M), 40S ribosomal protein S15a (RPS15A), ubiquitously expressed transcript (UXT), mitochondrial GTPase 1 (MTG1), 18S rRNA (RN18S1), and ubiquitin (UBC)] were evaluated. Three genes, β-casein (CSN2), lactoferrin (LTF), and cathelicidin (CAMP) were chosen as target genes. Very high amplification was observed in 7 ICG and very low level amplification was observed in 2 ICG (UXT and MTG1). Thus, UXT and MTG1 were excluded from further analysis. The qPCR data were analyzed by 2 software packages, geNorm and NormFinder, to determine suitable reference genes, based on their stability and expression. Overall, PPP1R11, ACTB, UBC, and GAPDH were stably expressed among all candidate reference genes. Therefore, these genes could be used as ICG for normalization of qPCR data in milk somatic cells through lactation.

Alteration of gene expression in mammary gland tissue of dairy cows in response to dietary unsaturated fatty acids

The aim of this study was to determine the effects of supplementing unprotected dietary unsaturated fatty acids (UFAs) from different plant oils on gene expression in the mammary gland of grazing dairy cows. A total of 28 Holstein-Friesian dairy cows in mid-lactation were blocked according to parity, days in milk, milk yield and fat percentage. The cows were then randomly assigned to four UFA sources based on rapeseed, soybean, linseed or a mixture of the three oils for 23 days, after which, all 28 cows were switched to a control diet for an additional 28 days. On the last day of both periods, mammary gland biopsies were taken to study genome-wide differences in gene expression on Affymetrix GeneChip® Bovine Genome Arrays (no. 900493) by ServiceXS (Leiden, The Netherlands). Supplementation with UFAs resulted in increased milk yield but decreased milk fat and protein percentages. Furthermore, the proportion of de novo fatty acids (FAs) in the milk was reduced, whereas that of long-chain FAs increased. Applying a statistical cut-off of false discovery rate of q-values <0.05 together with an absolute fold change of 1.3, a total of 972 genes were found to be significantly affected through UFA supplementation, indicating that large transcriptional adaptations occurred in the mammary gland when grazing dairy cows were supplemented with unprotected dietary UFA. Gene sets related to cell development and remodeling, apoptosis, nutrient metabolic process, as well as immune system response were predominantly downregulated during UFA supplementation. Such molecular knowledge on the physiology of the mammary gland might provide the basis for further functional research on dairy cows.

Lipopolysaccharide and lipoteichoic acid induce different immune responses in the bovine mammary gland

Different pathogens, such as Escherichia coli and Staphylococcus aureus, can be responsible for different outcomes of mastitis; that is, acute and severe or chronic and subclinical. These differences in the disease could be related to different mammary responses to the pathogens. The objective of this study was to determine if intramammary challenge with the endotoxins lipopolysaccharide (LPS), from E. coli, and lipoteichoic acid (LTA), from Staph. aureus, induce different immune responses in vivo in milk cells and mammary tissue. To provide a reference level for comparing the challenge and to show the different stimulation of the mammary immune system on a quantitatively similar level, dosages of LPS and LTA were chosen that induced an increase of somatic cells in milk to similar maxima. One udder quarter in each of 21 lactating dairy cows was challenged with 0.2 μg of LPS or 20 μg of LTA. From these quarters and from respective control quarters, milk cells or tissue biopsies were obtained at 0, 6, and 12h relative to the challenge to measure mRNA expression of tumor necrosis factor-α (TNFα), IL-1β, IL-8, lactoferrin, and RANTES (regulated upon activation, normal T-cell expressed and secreted). Furthermore, if no biopsies were performed, hourly milk samples were taken for measurement of somatic cell count, lactate dehydrogenase (LDH), and TNFα. Somatic cell count increased in all treatments to similar maxima with LPS and LTA treatments. Concentrations of TNFα in milk increased with LPS but not with LTA. The activity of LDH in milk increased in both treatments and was more pronounced with LPS than with LTA. The mRNA expression of TNFα, IL-1β, IL-8, and RANTES showed increases in milk cells, and LPS was a stronger inducer than LTA. Lactoferrin mRNA expression decreased in milk cells with LPS and LTA treatments. The measured factors did not change in either treatment in mammary tissue. Challenge of udder quarters with dosages of LPS and LTA that induce similar increases in SCC stimulate the appearance of different immune factor patterns. This dissimilar response to LPS and LTA may partly explain the different course and intensity of mastitis after infection with E. coli and Staph. aureus, respectively.

Expression of enzymes involved in the synthesis of prostaglandin E2 in bovine in vitro-produced embryos

Prostaglandin E2 (PGE2) may play a major role in embryo development and the establishment of pregnancy in cattle. The biosynthesis of PGE2 implies the sequential transformation of arachidonic acid to PGH2 by cyclooxygenases (COXs), then the conversion of PGH2 to PGE2 by prostaglandin E synthases (PGESs). Quantitative RT-PCR was used to examine the expression of COX-1, COX-2, microsomal PGES-1 (mPGES-1), microsomal PGES-2 (mPGES-2) and cytosolic PGES (cPGES) mRNAs in day 7 in vitro-produced (IVP) embryos from oocytes collected by ovum pick-up in Holstein heifers. Transcripts for COX-2 and mPGES-1 were detected in all embryos, whereas transcripts for COX-1 and mPGES-2 were not detected and cPGESs were at the limit of detection in 40% of embryos. Levels of COX-2 and mPGES-1 mRNAs were significantly higher in blastocysts and expanded blastocysts than in morulae and early blastocysts. Furthermore, excellent-quality embryos (grade 1) displayed higher levels of both COX-2 and mPGES-1 than did embryos of good and medium qualities (grades 2-3). Our results suggest that bovine IVP embryos at the morula and blastocyst stages use exclusively the COX-2/mPGES-1 pathway for PGE2 biosynthesis, and that PGE2 is potentially involved in blastocyst expansion and developmental competence.

Mastitis associated transcriptomic disruptions in cattle

Mastitis is ranked as the top disease for dairy cattle based on traditional cost analysis. Greater than 100 organisms from a broad phylogenetic spectrum are able to cause bovine mastitis. Transcriptomic characterization facilitates our understanding of host-pathogen relations and provides mechanistic insight into host resistance to mastitis. In this review, we discuss effector mechanisms and transcriptomic changes within the mammary gland in response to experimental infections. We compare temporal, spatial and pathogen-specific local transcriptomic disruptions in the mammary gland as well as pathogen-induced systemic responses and transcriptional changes in distant organs. We attempt to explain why studies on transcriptomic changes during critical physiological periods and in response to non-mastitic pathogens may have important implications for mastitis studies. Future perspectives on revealing bidirectional molecular cross-talk between mastitis pathogens and host cells using cutting-edge genomic technologies are also discussed.

Immune response of bovine milk somatic cells to endotoxin in healthy quarters with normal and very low cell counts

Low somatic cell count (SCC) is a reliable indicator of high-quality milk free of pathogenic microorganisms. Thus, an important goal in dairy practice is to produce milk with low SCC. Selection for cows with low SCC can sometimes lead to extremely low SCC in single quarters. The cells in milk are, however, predominantly immune cells with important immune functions. To investigate the mammary immune competence of quarters with very low SCC, healthy udder quarters of cows with normal SCC of (40–100)×103cells/ml and very low SCC of <20×103cells/ml were challenged with lipopolysaccharide (LPS) fromEscherichia coli. In the first experiment, SCC and cell viability after a challenge with 50 ng of LPS/quarter was investigated. In the second experiment, tumour necrosis factor α (TNF-α) concentration and lactate dehydrogenase (LDH) activity in milk, and mRNA expression of various innate immune factors in milk cells were measured after a challenge with 100 μg LPS/quarter. LPS challenge induced an increase of SCC. SCC levels reached were higher in quarters with normal SCC and maximum SCC was reached 1 h earlier than in very low SCC quarters. The increase of TNF-α concentrations in milk in response to LPS challenge was lower in quarters with very low SCC than in quarters with normal SCC. The viability of cells and the LDH activity in milk increased in response to LPS challenge, however, without a difference between the groups. The mRNA expression of IL-1β and IL-8 was increased in milk cells at 12 h after LPS challenge, whereas that of TNF-α and lactoferrin was not increased at the measured time points (12, 24 and 36 h after LPS challenge). No differences of mRNA expression of measured immune factors between normal and very low SCC samples were detected. The study showed that udder quarters with very low SCC responded with a less marked increase of SCC compared with quarters with normal SCC. This difference corresponded with simultaneously lower TNF-α concentrations in milk. However, the immune competence of the cells themselves based on mRNA expression of TNF-α, IL-8, IL-1β, and lactoferrin, did not differ. The results may indicate that very low SCC can impair the immune competence of udder quarters, because the immune response in udder quarters with lower SCC is less efficient as fewer cells contribute to the production of immunoregulators.

Selection and use of reference genes in mouse mammary glands

Obtaining quantitative data concerning gene expression is important for understanding milk synthesis in mammary glands. Quantitative real-time PCR (qRT-PCR) is an efficient tool to calculate gene expression; however, it is necessary to find valid reference genes for normalization of qRT-PCR data. We applied the geNorm software to eight commonly used reference genes to identify the most stable and optimal genes for the mouse mammary gland. Based on this analysis, HPRT, RPL and GAPDH are the most appropriate reference genes for data normalization. We tested the expression of the alpha-lactalbumin and fatty acid synthase genes using these three reference genes, both normalized and non-normalized. The normalized mRNA expression ratio was significantly different from the non-normalized ratio. We recommend the use of these three reference genes for the normalization of qRT-PCR data in gene expression studies of mouse mammary glands.

Database of cattle candidate genes and genetic markers for milk production and mastitis

A cattle database of candidate genes and genetic markers for milk production and mastitis has been developed to provide an integrated research tool incorporating different types of information supporting a genomic approach to study lactation, udder development and health. The database contains 943 genes and genetic markers involved in mammary gland development and function, representing candidates for further functional studies. The candidate loci were drawn on a genetic map to reveal positional overlaps. For identification of candidate loci, data from seven different research approaches were exploited: (i) gene knockouts or transgenes in mice that result in specific phenotypes associated with mammary gland (143 loci); (ii) cattle QTL for milk production (344) and mastitis related traits (71); (iii) loci with sequence variations that show specific allele-phenotype interactions associated with milk production (24) or mastitis (10) in cattle; (iv) genes with expression profiles associated with milk production (207) or mastitis (107) in cattle or mouse; (v) cattle milk protein genes that exist in different genetic variants (9); (vi) miRNAs expressed in bovine mammary gland (32) and (vii) epigenetically regulated cattle genes associated with mammary gland function (1). Fourty-four genes found by multiple independent analyses were suggested as the most promising candidates and were further in silico analysed for expression levels in lactating mammary gland, genetic variability and top biological functions in functional networks. A miRNA target search for mammary gland expressed miRNAs identified 359 putative binding sites in 3'UTRs of candidate genes.

Analysis of key molecules of the innate immune system in mammary epithelial cells isolated from marker-assisted and conventionally selected cattle

Mastitis is the most prevalent infectious disease in dairy herds. Breeding programs considering mastitis susceptibility were adopted as approaches to improve udder health status. In recent decades, conventional selection criteria based on phenotypic characteristics such as somatic cell score in milk have been widely used to select animals. Recently, approaches to incorporate molecular information have become feasible because of the detection of quantitative trait loci (QTL) affecting mastitis resistance. The aims of the study were to explore molecular mechanisms underlying mastitis resistance and the genetic mechanisms underlying a QTL on Bos taurus chromosome 18 found to influence udder health. Primary cell cultures of mammary epithelial cells from heifers that were selected for high or low susceptibility to mastitis were established. Selection based on estimated pedigree breeding value or on the basis of marker-assisted selection using QTL information was implemented. The mRNA expression of 10 key molecules of the innate immune system was measured using quantitative real-time PCR after 1, 6, and 24 h of challenge with heat-inactivated mastitis pathogens (Escherichia coli and Staphylococcus aureus) and expression levels in the high and low susceptibility groups were compared according to selection criteria. In the marker-assisted selection groups, mRNA expression in cells isolated from less-susceptible animals was significantly elevated for toll-like receptor 2, tumor necrosis factor-alpha, IL-1beta, IL-6, IL-8, RANTES (regulated upon activation, normal t-cell expressed and secreted), complement factor C3, and lactoferrin. In the estimated pedigree breeding value groups, mRNA expression was significantly elevated only for V-rel reticuloendotheliosis viral oncogene homolog A, IL-1 beta, and RANTES. These observations provide first insights into genetically determined divergent reactions to pathogens in the bovine mammary gland and indicate that the application of QTL information could be a successful tool for the selection of animals resistant to mastitis.

Cell population, viability, and some key immunomodulatory molecules in different milk somatic cell samples in dairy cows

Immune cells in the milk are most important in combating pathogens that invade the mammary gland. This study investigated the immune competence and viability of somatic milk cells that are already resident in milk and udders free of infection. Cells were studied in freshly removed milk to simulate conditions in the udder. Effects of incubation, cell preparation, and immunological stimulation with 0·5 μg/ml lipopolysaccharide (LPS) fromEscherichia coliwere analysed. Viability and differential counts of milk cells between high and low somatic cell count (SCC) quarters, and cisternal and alveolar milk with and without LPS stimulation were compared. Incubation and preparation of cells caused a cell loss which further increased with time independently of SCC and milk fraction. The viability of these cells was stable until 3 h post incubation and decreased until 6 h. Cell populations differed between both investigations, but did not change during the course of the experiment. mRNA expression of immune and apoptosis factors of the cells, measured by qPCR, did not change substantially: mRNA expression of caspase 3, Toll like receptor 4, and GM-CSF did not change, whereas the expression of the death receptor Fas/APO-1 (CD95), lactoferrin and lysozyme was decreased at 6 h. Cyclooxygenase-2 and TNF-α mRNA expression were decreased after 6 h of LPS treatment. In comparison with other studies in vivo or in vitro (in cell culture), in this study where cells are studied ex vivo (removed from the udder but kept in their natural environment, the milk) resident milk cells seem to be more vulnerable, less viable, less able to respond to stimulation, and thus less immune competent compared with cells that have freshly migrated from blood into milk after pathogen stimulation. The cell viability and differential cell count differed between high- and low-SCC milk and between cisternal and alveolar milk depending on the individual cow. In conclusion, the results support the view that for a most effective defence against invading pathogens the mammary gland is reliant on the recruitment of fresh immune cells from the blood.

Humoral and cellular factors of maternal immunity in swine

Immunoglobulins cannot cross the placenta in pregnant sows. Neonatal pigs are therefore agammaglobulinemic at birth and, although immunocompetent, they cannot mount rapid immune responses at systemic and mucosal sites. Their survival depends directly on the acquisition of maternal immunity via colostrum and milk. Protection by maternal immunity is mediated by a number of factors, including specific systemic humoral immunity, involving mostly maternal IgG transferred from blood to colostrum and typically absorbed within the first 36 h of life. Passive mucosal immunity involves local humoral immunity, including the production of secretory IgA (sIgA), which is transferred principally via milk until weaning. The mammary gland (MG) produces sIgA, which is, then secreted into the milk via the poly-Ig receptor (pIgR) of epithelial cells. These antibodies are produced in response to intestinal and respiratory antigens, including pathogens and commensal organisms. Protection is also mediated by cellular immunity, which is transferred via maternal cells present in mammary secretions. The mechanisms underlying the various immunological links between MG and the mucosal surfaces involve hormonally regulated addressins and chemokines specific to these compartments. The enhancement of colostrogenic immunity depends on the stimulation of systemic immunity, whereas the enhancement of lactogenic immunity depends on appropriate stimulation at induction sites, an increase in cell trafficking from the gut and upper respiratory tract to the MG and, possibly, enhanced immunoglobulin production at the effector site and secretion in milk. In addition, mammary secretions provide factors other than immunoglobulins that protect the neonate and regulate the development of mucosal immunity--a key element of postnatal adaptation to environmental antigens.

Staphylococcus aureus and Escherichia coli cause deviating expression profiles of cytokines and lactoferrin messenger ribonucleic acid in mammary epithelial cells

Pathogens invading the mammary gland cause a complex signaling network that activates the early immune defense and leads to an outcome of inflammation symptoms. To examine the importance of mammary epithelial cells in these regulations and interactions resulting in a pathogen-related course of mastitis, we characterized the mRNA expression profile of key molecules of the innate immune system by quantitative real-time PCR. Mammary gland epithelial cells isolated on d 42 of lactation from 28 first-lactation Holstein dairy cows were cultured separately under standardized conditions and treated for 1, 6, and 24 h with heat-inactivated gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. Both pathogens increased mRNA expression patterns of proteins involved in pathogen recognition such as Toll-like receptors and nuclear factor-kappa B, whereas gram-negatives acted as a stronger stimulus. Furthermore, this could be confirmed by the expression profile of the proinflammatory cytokines tumor necrosis factor alpha, IL-1 beta, IL-6, and chemokines such as IL-8 and RANTES (regulated upon activation, normal T-cell expressed and secreted). Remarkably, at a low level of mRNA expression after 1 h of treatment these cytokines and chemokines were expressed at a significantly higher level in Staphyloccocus aureus than in Escherichia coli affected cells. Lactoferrin showed a deviating expression pattern to pathogen stimulation (i.e., at the 1-h measuring point Escherichia coli induced a higher mRNA expression, whereas the highest level was reached after 24 h of stimulation with Staphylococcus aureus). Complement factor 3 was the only measured factor that responded equally to both microorganisms. Our data emphasize the role of mammary epithelial cells in the immune defense of the udder and confirm their contribution to pathogen-related different courses of mastitis.

Effect of the luteinising hormone surge on regulation of vascular endothelial growth factor and extracellular matrix-degrading proteinases and their inhibitors in bovine follicles

The aim of the present study was to evaluate the pattern of regulation of vascular endothelial growth factor (VEGF)-A (isoforms 121, 165, 189), VEGF receptor tyrosine kinases (VEGF-R1 and VEGF-R2), matrix metalloproteinase (MMP)-1, MMP-2, MMP-14, MMP-19, tissue-specific inhibitor of metalloproteinases (TIMP)-1, TIMP-2, tissue plasminogen activator (tPA), urokinase plasminogen activator (uPA), urokinase plasminogen activator receptor (uPAR) and plasminogen activator inhibitor-1 (PAI-1) in time-defined follicle classes before (0 h) and after the application of gonadotrophin-releasing hormone (GnRH). Bovine ovaries containing periovulatory follicles or new corpora lutea (CL; Days 1-2) were collected 0, 4, 10, 20 and 25 h (follicles) or 60 h (CL) after the injection of GnRH. Transcripts of VEGF isoforms (VEGF(121), VEGF(165), VEGF(189)) were upregulated 4 h after GnRH injection (during the luteinising hormone (LH) surge) and decreased thereafter to lowest levels around ovulation. All VEGF isoforms and their receptors were upregulated again after ovulation. The VEGF peptide concentration in follicular fluid decreased 20 h after GnRH injection, followed by an increase in follicles 25 h after GnRH. Expression of MMP-1 mRNA increased rapidly 4 h after GnRH injection and remained high during the entire experimental period. In contrast, MMP-19 mRNA increased significantly only after ovulation. Expression of TIMP-1 mRNA increased 4 h after GnRH and again after ovulation. Expression of tPA mRNA increased 4 h after GnRH and remained high during the entire experimental period, whereas expression of uPA transcripts increased significantly only after ovulation. Both uPAR and PAI-1 mRNA levels increased in follicles 4 h after GnRH and again after ovulation. The amount of MMP-1 protein (immunolocalisation) increased in follicles 10 h after GnRH: additional staining was observed in the granulosa cell layer. In conclusion, the temporal and spatial pattern of regulation of VEGF and extracellular matrix-degrading proteinases during periovulation suggests they are important mediators of the LH-dependent rupture of bovine follicles and for early CL formation (angiogenesis).

Proinflammatory cytokine mRNA expression in mammary tissue of sows following intramammary inoculation with Escherichia coli

The expression of the proinflammatory cytokines interleukin-1beta (IL-1beta), IL-6, IL-8, and tumor necrosis factor-alpha (TNF-alpha) mRNAs was determined by reverse transcription-PCR (RT-PCR) analysis of biopsies from the mammary glands of sows. The biopsies were collected before and 24h after intramammary inoculation of 12 pregnant sows with Escherichia coli (E. coli). Four of the sows developed clinical signs of mastitis and these animals displayed significantly lower levels of IL-1beta mRNA before inoculation than those that remained clinically healthy. There was a significant increase in IL-1beta, IL-6, IL-8, and TNF-alpha mRNA expression in the inoculated mammary glands of sows that developed clinical signs of mastitis (affected group) 24h postinoculation. This was also true for IL-8 and TNF-alpha mRNA expression in the inoculated mammary glands of sows that did not develop clinical signs of mastitis (non-affected group). No significant differences were found in IL-1beta, IL-6, and TNF-alpha mRNA expression in the inoculated mammary glands between groups (affected versus non-affected) 24h postinoculation. Thus, a local production of proinflammatory cytokines in the mammary gland of sows was indicated by the induced expression of IL-1beta, IL-6, IL-8, and TNF-alpha mRNAs after intramammary inoculation with E. coli.

Endoscopic Examination and Tissue Sampling of the Bovine Teat and Udder Cistern

The aim of this study was to evaluate the application of an endoscopic technique to investigate the teat and udder cisterns of the bovine mammary gland, and to biopsy tissues within the cisterns. An anesthetic protocol for application in standing animals was designed, using a combination of general and local anesthesia. Individual quarter milk production (QMP), quarter somatic cell count (SCC), and occurrence of new intramammary infection were assessed after application of the technique, and possible applications for biopsies collected were investigated. Bovine teat and gland cistern lining could be visualized and small biopsy samples could be collected. The collected biopsy samples were successfully used in histological-histopathological examination and PCR analysis. To study the impact of endoscopy on QMP, milk SCC, and bacteriology, endoscopic examination of 12 low SCC (<200,000 cells/ mL) quarters was performed in 8 different first- and second-lactation cows. Immediately following endoscopy, 8 quarters received antibiotic treatment, whereas 4 quarters remained untreated. During a 15-d follow-up, no new intramammary infection could be observed in the endoscopically treated quarters. For QMP, no significant interaction between time and treatment could be observed throughout the 15-d follow-up period. Quarter SCC did not differ among treatments (control, endoscopy with antibiotics, and endoscopy without antibiotics). In conclusion, the endoscopic technique is suitable for examination and tissue biopsy collection of the bovine mammary gland cisterns without major interference with QMP and quarter SCC.

Changes in fibroblast growth factor 2 and its receptors in bovine follicles before and after GnRH application and after ovulation

The aim of this study was to evaluate the expression pattern of fibroblast growth factor 2 (FGF2), its receptor variants (FGFR1IIIc, FGFR2IIIc) and nucleolin in time-defined follicle classes before and after GnRH application and after ovulation in the cow. Ovaries containing preovulatory follicles or new corpora lutea (CL) were collected at approximately 0, 4, 10, 20 and 25 h (follicles) and 60 h (new CL) relative to injection of GnRH to induce an LH surge (n = 5 animals per group). The expressions of FGF2 and FGFR1IIIc mRNA were significantly up-regulated only in the follicle group 4 h after GnRH (during the LH surge) with a significant down-regulation immediately afterwards. Western blot analyses showed two protein bands with at 22 and 18 kDa with apparent up-regulation beginning with the LH surge (4 h) and maximum levels 20 h after GnRH. FGF2 protein in follicles collected at 0 h (before LH surge) was localised in theca tissue (endothelial and pericytes of blood vessels) but not in granulosa cells (GCs). The FGF2 staining (by immunohistochemistry) pattern changed dramatically after the LH surge for a short period (about 2 days) and FGF2 protein was localised dominantly in the nucleus of many GCs, while most capillary endothelial cells were FGF2 immunonegative. In conclusion, the novel observation of FGF2 up-regulation and the distinct change in FGF2 localisation from theca (cytoplasm of endothelial cells) to the nucleus of GCs after the LH surge may be important for survival of GCs or for the transition of the GCs to luteal cells.

Short-term effects on pro-inflammatory cytokine, lactoferrin and CD14 mRNA expression levels in bovine immunoseparated milk and blood cells treated by LPS

Leucocytes (WBC) are recruited from peripheral blood into milk as part of the inflammatory response, mediated through cytokines or interleukins (IL) synthesized by mammary tissue and the milk somatic cells (SC). The inflammatory response is related to the concentration of SC and the cytokines produced. To investigate and to compare the kinetics of cytokine production in SC and WBC during inflammation, cell culture models were established, where SC and WBC were cultured in parallel (n = 3). In addition, macrophages or monocytes were isolated from milk and blood with antibody-coated magnetic beads and cultivated separately. Isolated cells were pure, unaltered and viable. Cultures were activated with 10 microg/ml lipopolysaccharide (LPS). After 0, 1, 2, 3, 4 and 8 h cells were harvested for RNA isolation. Cytokine [tumour necrosis factor alpha (TNFalpha), IL-1beta, IL-6] mRNA expression responses and transcriptional activity of CD14 and lactoferrin (LF) were quantified via a one-step real-time RT-PCR. Significant cytokine mRNA increases were found in all four cell culture types and genes, with peaks after 1 and 2 h (TNFalpha > IL-6 > IL-1beta). In WBC or monocytes higher LPS responses and longer persistence could be found than in corresponding milk cells (IL-1beta > IL-6 > TNFalpha). SC and macrophages are less responsive to LPS stimulation than WBC or monocytes. The strength of the immune response in the blood system is much more prominent than in the mammary gland. This may be ascribed to the role of CD14 on the cytokine production of the investigated cells, or may be caused by the blood-to-milk diapedesis. The constitutive transcription of CD14 mRNA in WBC and monocytes was found to be 6 to 15 times higher than in adequate milk cells.

Lipopolysaccharide and lipoteichoic acid induce different innate immune responses in bovine mammary epithelial cells

The objective of the present study was to characterize the innate immune responses induced by in vitro stimulation of bovine primary mammary epithelial cells (bMEC) using gram-negative lipopolysaccharide (LPS) and gram-positive lipoteichoic acid (LTA) bacterial cell wall components. Quantitative real-time PCR (qRT-PCR) was employed to examine the mRNA expression of a panel of 22 cytokines, chemokines, beta-defensins and components of the Toll-Like Receptor signaling pathway. Stimulation of bMEC with LPS for 24h elicited a marked increase in mRNA expression for IL-1beta, IL-8, TNFalpha, CXCL6 and beta-defensin while members of the Toll-Like Receptor pathway, although present, were largely unaffected. Surprisingly, stimulation of these cells with LTA for 24 h did not significantly alter the expression of these genes. A time course of the expression of IL-1beta, IL-8, TNFalpha, CXCL6 and beta-defensin was subsequently performed. The mRNA levels of all genes increased rapidly after stimulation for 2-4 h with both LPS and LTA but only the former treatment resulted in sustained responses. In contrast, the increased gene expression for LTA stimulated cells returned to resting levels after 8-16 h with the exception of beta-defensin, which remained up-regulated. The limited and unsustained cytokine response to LTA may explain why mastitis caused by gram-positive bacteria has greater potential for chronic intra-mammary infection than gram-negative infection. It was concluded that bovine mammary epithelial cells have a strong but differential capacity to mount innate immune responses to bacterial cell wall components.

Effects of an enhanced vitamin A intake during the dry period on retinoids, lactoferrin, IGF system, mammary gland epithelial cell apoptosis, and subsequent lactation in dairy cows

Studies in vitro show important interactions among vitamin A, lactoferrin, and insulin-like growth factor (IGF) binding proteins (IGFBP) and, thus, the IGF system. As a consequence, mammary gland epithelial cell proliferation and apoptosis during the bovine dry period and potential milk yield may be affected. We have studied effects of feeding vitamin A (550,000 IU/ d) that exceed daily requirements about 8-fold for up to 2 mo to dairy cows during the dry period on concentrations of retinol and its metabolites in plasma and milk, milk lactoferrin, plasma and milk IGF-I and IGFBP-3, lactoferrin and IGF-I mRNA levels in mammary gland tissue, mammary gland apoptosis, and 100-d milk yield in the ensuing lactation. In the group supplemented with vitamin A, the peripartal decrease of plasma retinol was delayed and attenuated, and colostral retinol plus retinylester concentration was enhanced, but colostral beta-carotene concentration decreased. The retinoic acid isomer 9,13-dicis retinoic acid that coeluted with 13-cis retinoic acid, was the predominant circulating retinoic acid and was higher in GrA than the control group. Plasma IGFBP-3 concentrations were positively correlated with plasma retinol concentrations (r = 0.51), but there were no group differences. Numbers of apoptotic epithelial cells in mammary epithelium were higher at drying off and parturition than in the middle of the dry period, coinciding with high concentrations of IGF-I and lactoferrin in mammary secretions. At parturition, numbers of apoptotic cells in mammary gland biopsies in cows supplemented with vitamin A were higher than in control cows. In conclusion, supplementation of dairy cows during the dry period with high amounts of vitamin A did not significantly modify concentrations of lactoferrin, IGFBP-3, and IGF-I in plasma and in mammary secretions, but slightly decreased energy-corrected 100-d milk yield and milk fat yield, possibly because of enhanced apoptic rates of mammary cells.

ArrayVigil: a methodology for statistical comparison of gene signatures using segregated-one-tailed (SOT) Wilcoxon's signed-rank test

Due to versatile diagnostic and prognostic fidelity molecular signatures or fingerprints are anticipated as the most powerful tools for cancer management in the near future. Notwithstanding the experimental advancements in microarray technology, methods for analyzing either whole arrays or gene signatures have not been firmly established. Recently, an algorithm, ArraySolver has been reported by Khan for two-group comparison of microarray gene expression data using two-tailed Wilcoxon signed-rank test. Most of the molecular signatures are composed of two sets of genes (hybrid signatures) wherein up-regulation of one set and down-regulation of the other set collectively define the purpose of a gene signature. Since the direction of a selected gene's expression (positive or negative) with respect to a particular disease condition is known, application of one-tailed statistics could be a more relevant choice. A novel method, ArrayVigil, is described for comparing hybrid signatures using segregated-one-tailed (SOT) Wilcoxon signed-rank test and the results compared with integrated-two-tailed (ITT) procedures (SPSS and ArraySolver). ArrayVigil resulted in lower P values than those obtained from ITT statistics while comparing real data from four signatures.

Leptin and prolactin modulate the expression of SOCS-1 in association with interleukin-6 and tumor necrosis factor-α in mammary cells: a role in differentiated secretory epithelium

Leptin and its receptors have been shown to be expressed in several tissues, suggesting that this protein might be effective not only at the CNS level but also peripherally. We have previously reported that leptin and its long form receptor are expressed in the mouse mammary epithelial cell line HC11. In this study, we report a specific relationship among leptin, prolactin (PRL), interleukin-6 (IL-6), and tumor necrosis-alpha (TNF-alpha) in the modulation of the suppressor of cytokine signaling 1 (SOCS-1). Furthermore, we show that leptin and PRL are able to effectively enhance SOCS-1 gene expression in the HC11 cell line. Finally, high concentrations of leptin (100 nM) and/or PRL significantly (p<0.05) reduce the inhibitory effect of IL-6 (10 and 100 ng/ml) and TNF-alpha (10 and 100 ng/ml) on beta-casein gene expression in HC11 cells transfected with pbetacCAT, a chimeric rat-beta casein gene promoter-cloramphenicol acetyl transferase (CAT) gene construct. These results provide evidence that leptin may be an important mediator in regulating mammary gland growth and development and that this role may be related to the immune factors that are involved in inflammation.

Short-term changes of mRNA expression of various inflammatory factors and milk proteins in mammary tissue during LPS-induced mastitis

During mammary gland infection, non-specific responses are the predominant ones. The goal of this study was to investigate the mRNA expression of various soluble immune components and of the major milk proteins during the acute phase of mammary inflammation. Five healthy lactating cows were intramammary infused in one quarter with 100 microg Escherichia coli-endotoxin (lipopolysaccharide, LPS) and the contralateral quarter with saline (9 g/l) serving as control. Mammary biopsy samples of both quarters were taken immediately before and at 3, 6, 9 and 12 h after infusion and mRNA expression of various factors was quantified via real-time RT-PCR. Blood samples for determination of leukocyte number were taken simultaneously with the biopsy samples and rectal temperature was measured at 1-h intervals. Rectal temperature increased until 5h (P < 0.05) after LPS administration and remained elevated until 9 h after LPS inoculation. Blood leukocyte number decreased (P < 0.05) from 0 to 3 h from 7.7 +/- 1.1 x 10(9)l(-1) to 5.7 +/- 1.0 x 10(9)l(-1) and thereafter recovered to pre-treatment levels until 12 h after LPS challenge. In LPS-treated quarters, tumor necrosis factor-alpha and cyclooxygenase-2-mRNA expression increased (P < 0.05) to highest values at 3h after LPS challenge. Lactoferrin, lysozyme, inducible nitric oxide synthase increased (P < 0.05) and peaked at 6 h after challenge, and platelet-activating factor acetylhydrolase-mRNA expression tended to increase (P = 0.07). mRNA expression of insulin-like growth factor-I and of alphaS1-casein (CN), alphaS2-CN, beta-CN and beta-lactoglobulin did not change significantly, whereas mRNA expression of 5-lipoxygenase and alpha-lactalbumin decreased (P < 0.05) in both quarters and that of kappa-CN only in the LPS quarter. mRNA expression of some investigated factors (tumor necrosis factor-alpha, lysozyme, 5-lipoxygenase, alpha-lactalbumin) changed in control quarters, however in all respective factors less than in the LPS quarters (P < 0.05). In conclusion, mRNA expression of most inflammatory factors increased within hours, whereas that of most milk proteins remained unchanged.

ArraySolver: an algorithm for colour-coded graphical display and Wilcoxon signed-rank statistics for comparing microarray gene expression data

The massive surge in the production of microarray data poses a great challenge for proper analysis and interpretation. In recent years numerous computational tools have been developed to extract meaningful interpretation of microarray gene expression data. However, a convenient tool for two-groups comparison of microarray data is still lacking and users have to rely on commercial statistical packages that might be costly and require special skills, in addition to extra time and effort for transferring data from one platform to other. Various statistical methods, including the t-test, analysis of variance, Pearson test and Mann-Whitney U test, have been reported for comparing microarray data, whereas the utilization of the Wilcoxon signed-rank test, which is an appropriate test for two-groups comparison of gene expression data, has largely been neglected in microarray studies. The aim of this investigation was to build an integrated tool, ArraySolver, for colour-coded graphical display and comparison of gene expression data using the Wilcoxon signed-rank test. The results of software validation showed similar outputs with ArraySolver and SPSS for large datasets. Whereas the former program appeared to be more accurate for 25 or fewer pairs (n < or = 25), suggesting its potential application in analysing molecular signatures that usually contain small numbers of genes. The main advantages of ArraySolver are easy data selection, convenient report format, accurate statistics and the familiar Excel platform.