Biomedical subjects

C Burvenich

Publications and source records attributed to C Burvenich.

At least 19 recordsLinked to original sources

PubMed2006

Analysis of iodinated peptides by LC-DAD/ESI ion trap mass spectrometry.

The analysis of iodinated peptides resulting from chloramine-T (CAT), Iodo-Beads, Iodo-Gen and lactoperoxidase iodination reactions in the preparation of nanomole quantities 125I and 123I labelled tracers is described. Seven different model peptides were evaluated, varying in molecular weight from 294 (LY-dipeptide) to 2518 (obestatin containing 23 amino acid residues). Two different RP-C18 columns were used, each with a different gradient system based on aqueous formic acid and acetonitrile. Electrospray ionization (ESI) ion trap mass spectrometry was used for identification of the chromatographic eluting components of the reaction mixtures, while UV (DAD) served quantitative purposes. Non-, mono-, di-, tri- and tetra-iodinated peptides (respectively NIP, MIP, DIP, 3IP and 4IP) eluted in that order and were well separated from each other. An empirical model was derived. The applicability of this approach was demonstrated by the analysis of different reaction mixtures.

Chromatography, High Pressure Liquid↗

PubMed2006

In vitro effects of nonesterified fatty acids on bovine neutrophils oxidative burst and viability.

An in vitro study was conducted to examine the influence of nonesterified fatty acids (NEFA) on bovine polymorphonuclear leukocytes (PMN). Eight healthy, midlactating Holstein cows were used as blood donors. Blood PMN were isolated and incubated with a mixture of NEFA, reflecting composition of bovine plasma NEFA at concentrations that were intended to mimic those found in blood of cows undergoing high, moderate, or low lipomobilization intensity (2, 1, 0.5, 0.25, 0.125, and 0.0625 mM). Control samples were incubated in absence of NEFA. Phagocytosis and oxidative burst activities were assessed by a 2-color flow cytometric method, which was based on oxidation of intracellular dihydrorhodamine 123 to green fluorescent rhodamine 123. Oxidative burst products were generated by incubating PMN with Staphylococcus aureus labeled with propidium iodide. A flow cytometric technique was used to detect PMN viability, necrosis, and apoptosis using fluorescein isothiocyanate-labeled annexin-V and propidium iodide. Phagocytic activity was not affected by NEFA. The highest concentration of NEFA (2 mM) was associated with a dramatic increase of phagocytosis-associated oxidative burst activities with a reduction in cell viability (48.0 vs. 97.5% in control samples) and with a marked increase of necrosis (49.4 vs. 0.5% in control samples). Conversely, the mixture of NEFA did not affect the occurrence of apoptosis. Enhancement of the oxidative burst associated with the highest concentration of NEFA might explain the reduced viability and higher percentage of necrosis observed under the same conditions. This study demonstrated a substantial resistance of bovine PMN to an overload of fatty acids. However, observation that the highest concentration of NEFA regulated some PMN functions encourages the possibility of in vivo studies to assess the relationships between intensity of lipomobilization, plasma NEFA, and bovine PMN functions.

Animals↗

PubMed2006

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.

Animals↗

PubMed2006

Mathematical model of the acute inflammatory response to Escherichia coli in intramammary challenge.

We constructed a mathematical model of the early response to Escherichia coli infection of the mammary gland and explored the roles and interactions between inflammatory cells and bacteria. The model incorporates 3 equations that describe the interactions among bacteria, milk somatic cells, and blood leukocyte densities. These 3 equations were fitted to cell densities observed during acute inflammatory responses in unvaccinated and vaccinated heifers inoculated with 10(4) or 10(6) cfu of E. coli. The rates computed for the cellular transit from the storage sites to the blood and from the blood to the milk were lower in cows receiving 10(4) cfu but increased at approximately 6 x 10(-6) and 30 x 10(-6) microL/cfu per h in nonvaccinated or vaccinated cows inoculated with 10(6) cfu, respectively. The cellular rates of bacterial killing were highest in unvaccinated cows ( approximately 400 x 10(-6) microL/cell per h) when compared with vaccinated cows (200 to 300 x 10(-6) microL/cell per h). A critical density of milk somatic cells at which bacteria density is constant was computed from the model at 2 x 10(6) cells/mL, and a one-way sensitivity analysis revealed that the changes in milk cellular densities were mostly sensitive to variations in the rate of bacterial killing and in the rate of production of inflammatory cells.

Animals↗

PubMed2006

Technical note: validation of internal control genes for gene expression analysis in bovine polymorphonuclear leukocytes.

Analysis of gene expression is becoming more important in all areas of biological research to evaluate gene expression during physiological and pathological conditions (e.g., mastitis), not the least in the field of animal research. Presently, real-time gene expression analysis is considered to be the method of choice for accurate and sensitive quantification of mRNA transcripts. Because comparison of gene expression levels is frequently the aim of these experiments, there is a critical need to validate internal control genes. When studying gene expression in bovine polymorphonuclear leukocytes, special attention should be paid to this validation, because polymorphonuclear leukocytes are subjected to numerous physiological influences, depending on the stage of lactation. In this study, 8 commonly used reference genes (ACT, GAPD, H2A, TBP, HPRT1, SDHA, YWHAZ, and 18S rRNA) were evaluated in bovine polymorphonuclear leukocytes. The transcription levels of 6 reference genes were determined using real-time PCR. By geometrically averaging the expression levels of these genes, SDHA, YWHAZ, and 18S rRNA were selected as being the most stable genes for accurate normalization of real-time results of bovine polymorphonuclear leukocytes.

Animals↗

PubMed2005

Expression of the estrogen receptor in blood neutrophils of dairy cows during the periparturient period.

During the period around parturition, cows experience an increased susceptibility to inflammatory disorders in the mammary gland and uterus. This increased susceptibility has been correlated with a decreased functionality of neutrophils, major components in the innate immune defence. As sex steroid levels vary extensively in the period around parturition, an influence of these changes on the functionality of neutrophils has been suggested. Indeed, it has been shown that 17beta-estradiol affects some functions of bovine neutrophils. In spite of these observations, receptors for 17beta-estradiol have not yet been demonstrated in these cells. The investigation of the presence of estrogen receptors in bovine neutrophils was therefore the main objective of this study. The expression of estrogen receptors was evaluated at the protein level by flow cytometry, and at the mRNA level by polymerase chain reaction. A clear positive signal was obtained using flow cytometry for the estrogen receptor protein in bovine neutrophils. Further discrimination between the estrogen receptor subtypes alpha and beta revealed the expression of the estrogen receptor beta, whereas for the estrogen receptor alpha no reproducible positive signal could be obtained with the available antibodies. Both subtypes were found at the mRNA level. Subsequently, the estrogen receptor protein expression level in neutrophils obtained from cows in early lactation was compared with those from cows in late pregnancy. Additionally, the influence of endogenous 17beta-estradiol and progesterone levels was assessed. No difference was found for the estrogen receptor protein expression in neutrophils from cows in early lactation compared with late gestation neither were the endogenous 17beta-estradiol and progesterone levels correlated with the protein expression.

Animals↗

PubMed2005

Physiology of the periparturient period and its relation to severity of clinical mastitis.

Incidence of clinical mastitis is highest at drying off and during the periparturient period. Intramammary Escherichia coli infection in high-yielding cows can show a severe clinical response during the early post-partum period. Severe clinical mastitis is mainly determined by cow factors, in particular the functionality of the circulating polymorphonuclear leukocytes (PMN) which are recruited to the mammary gland during the inflammatory reaction. There is a co-incidence between the periods of highest incidence of clinical mastitis and specific structural changes in the mammary gland. During the periparturient period, marked changes in various systemic and local hormones are related to the secretory state of the mammary gland epithelium (lactogenesis). Estrogen and progesterone induce proliferation of the mammary epithelium throughout gestation and act as survival factors in different tissues, although conflicting data have been reported on their effect on PMN oxidative burst. Somatotropin (STH), responsible for maintenance of lactation in ruminants, has been shown to positively influence innate immunity and a more rapid recovery in milk production of severely affected animals. The concentration of STH, and as a result also IGF-I levels is, however, quite low during early lactation. IGF-I and its regulating binding proteins are associated with cell survival, modulation of apoptosis and functionality of PMN in humans. During early lactation, bio-availability of IGF-I is decreased, which might reduce its stimulating effects on PMN quality and functionality. PRL, concomitantly known as a lactogenic hormone and an immunoregulatory cytokine, has also been associated with modulation of the immune system. It is expected that in periparturient animals, hormone changes could interfere with the immune response and the clinical response of mastitis.

Animals↗

PubMed2005

Effect of carprofen treatment following experimentally induced Escherichia coli mastitis in primiparous cows.

Acute Escherichia coli mastitis is one of the major sources of economic loss in the dairy industry due to reduced milk production, treatment costs, discarded milk, and occasional fatal disease. Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently used as adjunctive therapy to antibiotics. The objective of the current study was to evaluate the effect of carprofen treatment following infusion of Escherichia coli into the mammary glands of primiparous cows during the periparturient period. Severity of mastitis was scored based on the average milk production in the uninfected quarters on d +2 postinoculation and a clinical severity score. Carprofen was administered intravenously at 9 h postchallenge, when clinical signs of mastitis appeared. In previous work, efficacy of NSAIDs was mainly evaluated using clinical symptoms. In the present study, the effect of carprofen on innate immune response was also assessed by quantification of inflammatory mediators. All primiparous cows reacted as moderate responders throughout the experimental period. Primiparous cows were intramammarily inoculated with 1 x 10(4) cfu of E. coli P4:O32 in 2 left quarters. Analysis of blood and milk parameters, including IL-8, complement component C5a, lipopolysaccharide-binding protein (LBP), soluble CD14, prostaglandin E2, and thromboxane B2 was performed from d 0 to d +6 relative to intramammary inoculation. Rectal temperature in carprofen-treated animals was lower than in control animals at 3 and 6 h posttreatment. Treatment also restored the decreased reticulorumen motility that occurs during E. coli mastitis to preinfection levels faster than in control animals. Carprofen treatment resulted in an earlier normalization of the clinical severity score. Eicosanoid (prostaglandin E2 and thromboxane B2) production in milk tended to be inhibited by carprofen. No significant differences in the kinetic patterns of somatic cell count, IL-8, complement component C5a, LBP, and soluble CD14 were observed. In conclusion, carprofen treatment improved general clinical condition by effective antipyrexia and restoration of reticulorumen motility but did not significantly inhibit eicosanoid production. Carprofen treatment did not result in a significant decrease of chemotactic inflammatory mediators, IL-8 and C5a, and early innate immune molecules, sCD14 and LBP. Therefore, major modulatory effects from NSAID administration were not observed in this mastitis model, although a larger study might confirm some apparent trends obtained in the present results.

Animals↗

PubMed2004

Sex steroids and growth factors in the regulation of mammary gland proliferation, differentiation, and involution.

The mammary gland is subjected to major morphological and biochemical changes during the lactation cycle. It is therefore not surprising that this dynamic process is strictly controlled. The importance of the sex steroid hormones 17beta-estradiol and progesterone for normal development of the mammary gland was recognized several decades ago and has been unequivocally confirmed since. Furthermore, it is now also established that the influence of sex steroids is not restricted to mammogenesis, but that these hormones also control involution. Another important regulatory role is played by growth factors that have been shown to modulate survival (epidermal growth factor, amphiregulin, transforming growth factor alpha, insulin like growth factor, and tumor necrosis factor alpha) or apoptosis (tumor necrosis factor alpha, transforming growth factor beta) of mammary cells. However, the molecular mechanism underlying the influence of sex steroid hormones and/or growth factors on the development and function of the mammary gland remains largely unknown to date. Also scarce is information on the interaction between both groups of modulators. Nevertheless, based on the current indications compiled in this review, an important functional role for sex steroid hormones in the lactation cycle in co-operation with growth factors can be suggested.

Animals↗

PubMed2004

Moderate inflammatory reaction during experimental Escherichia coli mastitis in primiparous cows.

Nineteen primiparous cows were experimentally infected in 2 quarters with 1 x 10(4) (group A) or 1 x 10(6) (group B) cfu of Escherichia coli P4:O32 per quarter within 2 to 4 wk after parturition. Blood and milk samples were collected from all primiparous cows at regular time intervals from d -4 to d +3 relative to inoculation. Milk production rapidly decreased in both groups during E. coli mastitis, but recovery appeared to be faster in group B at d + 1 postinfusion (p.i.). The milk production losses in the noninfected quarters were substantial on the day of inoculation, which is probably due to pronounced systemic effects. However, on d + 2 p.i. milk production in the noninfected quarters nearly reached preinfection levels, indicating a moderate clinical severity following intramammary inoculation. None of the other severity criteria evolved towards a severe response pattern. Reticulorumen motility was inhibited in both groups during E. coli mastitis. The clinical episode was short lasting in both groups. Rectal temperature, heart rate, blood leukocyte count, number of colony-forming units, milk somatic cell count and several indicators for the disintegration of the blood-milk barrier returned to normal values within 24 to 72 h p.i. Primiparous cows reacted with a moderate inflammatory response following intramammary infusion with a relatively high dose of E. coli. Despite the use of a high inoculum dose, primiparous cows in both groups showed pronounced resistance against severe intramammary E. coli infection. A possible effect of the inoculum dose could be present, however, further research into the effect of the inoculum dose on the inflammatory response should be performed.

Animals↗

PubMed2004

All-trans retinoic acid is increased in the acute phase-related hyporetinemia during Escherichia coli mastitis.

Blood vitamin A profiles, including concentrations of retinol and its active metabolite retinoic acid, were assessed during the peripartum period and during experimentally induced Escherichia coli mastitis in heifers. Serum retinol decreased in all animals in the immediate postpartum period and normalized within 1 wk after parturition. No significant changes were detectable in the concentrations of retinoic acid isomers during puerperium. Following intramammary E. coli infusion, all cows showed moderate symptoms of systemic disease besides the local signs of inflammation. The presence of a systemic acute-phase reaction was documented by fever, increase in serum amyloid A, and decrease in serum albumin. Retinol concentration in serum also decreased spectacularly during coliform mastitis, and the decline was clearly related to the timing of the acute-phase response. Moreover, a significant increase of all-trans retinoic acid, mirrored by a lowering of 13-cis retinoic acid, was detected during the same time period. The 9-cis isomer of retinoic acid was present in all samples, but it remained below the quantification limit. Results confirmed the decrease in serum retinol during the peripartum period of dairy cows. Furthermore, the study established that profound changes in vitamin A metabolism occur during the acute-phase reaction of coliform mastitis in heifers. The bovine infection model reproduced the acute phase-related hyporetinemia, as previously observed in humans and rats. In addition, all-trans retinoic acid was found to be the most abundant circulating acid isomer during mastitis, providing an indication for a possible key role of all-trans retinoic acid in the modulation of the immune response.

Acute-Phase Reaction↗

PubMed2004

Differential effects of steroids and retinoids on bovine myelopoiesis in vitro.

Pregnancy and parturition are associated with physiological changes caused by steroid hormones. Alterations in number, maturity, and function of polymorphonuclear leukocytes observed in dairy cows at parturition suggest a common causative relationship with steroid hormones. This study was designed to investigate the effects of progesterone, 17-beta-estradiol, and hydrocortisone on the proliferation of bovine progenitor cells. An in vitro culturing system was used, and colonies were scored after 7 d of incubation. At low concentrations, 17-beta-estradiol inhibited proliferation of granulocyte progenitor cells. Hydrocortisone reduced growth of granulocyte and monocyte colonies, whereas myelopoiesis was not altered by progesterone. Furthermore, we studied the effect of retinoids on colony formation of bovine bone marrow cells. All-trans- and 9-cis-retinoic acid stimulated growth of granulocyte colonies and inhibited proliferation of the monocyte lineage. The addition of the 13-cis-isomer also increased numbers of granulocyte colony-forming units. This study indicates that steroid hormones may be responsible for alterations in the bovine hematopoietic profiles observed in circulation during the postpartum period. White blood cells, especially polymorphonuclear leukocytes, which are derived from bone marrow, are an important first line defense against mastitis. Therefore, these effects of steroids might contribute to the increased susceptibility of dairy cows to Escherichia coli mastitis. We furthermore hypothesize that an important role might be attributed to retinoic acid in its regulation of bovine myelopoiesis. Modulation of myelopoiesis in favor of the granulocyte lineage during the acute-phase reaction may be an adaptive mechanism designed to increase the capacity of first-line defense to intramammary infections.

Animals↗

PubMed2004

Proteolysis in milk during experimental Escherichia coli mastitis.

This work consisted of the intramammary infections (IMI) of 8 heifers by high doses of Escherichia coli to study both the proteolytic activity in milk and the resulting peptides. Therefore, a milking kinetic has been followed, and several parameters have been studied, such as proteose peptones (PP) fraction (quantitative and qualitative changes), plasmin activity (PA), milk somatic cell count (SCC), and bacterial count. A qualitative study of milk proteins and PP was performed by sodium dodecyl sulfate-PAGE, and the peptides recovered in PP during the acute phase of inflammation were amino-terminal micro-sequenced. A BSA increase in milk over time supported the hypothesis of an increase in the permeability of the epithelial barrier. A significant increase in PP content, considered to be an indicator of proteolysis, was observed from postinfusion hours (PIH) 12 to 48. Both the E. coli bacterial count and the SCC increased from PIH 3 to 216. Plasmin activity was increased noticeably from PIH 15 to 24. The respective increases in SCC, bacterial count, and PA suggest their involvement in a global mechanism responsible for the increase in proteolysis in milk after E. coli challenge. Somatic cell count and E. coli may be involved from PIH 3 to 216, and PA involvement might be highlighted during the maximum proteolysis, from PIH 15 to 24. A qualitative study of PP fraction by electrophoresis revealed the apparition of 5 peptide bands: P1 and P2 previously recovered during the lipopolysaccharide challenge, and E1 (27.0 kDa), E2 (15.5 kDa), and E3 (9.0 kDa) were specific to E. coli challenge; E1, E2, and E3 contained casein fragments. The roles played by leukocytes and E. coli are discussed.

Animals↗

PubMed2004

Influence of 17beta-estradiol, progesterone, and dexamethasone on diapedesis and viability of bovine blood polymorphonuclear leukocytes.

The aim of the current study was to investigate whether polymorphonuclear leukocyte (PMN) diapedesis and viability are influenced by steroid hormones. Using an in vitro model with different types of cell layers (bovine mammary epithelial cells and fibroblasts), we investigate whether steroid hormone treatments (17beta-estradiol, progesterone, and dexamethasone) have an influence on the diapedesis capacity and viability of PMN. In addition, we studied apoptosis of PMN in the in vitro model and evaluated the influence of different types of cell layers and steroid hormone treatments on this process. A significant decrease in the number of viable PMN in the lower compartment of the in vitro model (i.e., number of migrated PMN x viability after migration) was found after 17beta-estradiol treatment, whereas no influence was detected after progesterone or dexamethasone treatment. The effect of 17beta-estradiol was not due to a lower viability before migration as none of the treatments caused a significant effect on the viability before diapedesis. This treatment effect was not influenced by endogenous 17beta-estradiol or progesterone levels before isolation because there was no correlation between these plasma levels and PMN diapedesis capacity or viability. Furthermore, migration through epithelial cells caused a significant decrease in viability of PMN due to increased apoptosis but not necrosis.

Animals↗

PubMed2004

L-selectin and chemotaxis throughout bone marrow granulocyte maturation in the bovine.

Polymorphonuclear neutrophilic leukocytes (PMNL) play a pivotal role during inflammation. Bone marrow (BM) reserves are depleted as cells are released into circulation for recruitment to infection sites. Expression of L-selectin on the cell membrane allows neutrophils to roll along the activated endothelium. Whereas mechanisms leading to recruitment to infection sites are well established, expression of BM adhesion molecules in cows is limited. In this study, we assessed L-selectin expression and chemotactic response to zymosan-activated serum (ZAS) in bovine BM cells and in circulating neutrophils. Isolated blood PMNL and BM cells were used from 9 dairy cows, for quantifying L-selectin expression using flow cytometry, and from 12 dairy cows for chemotaxis studies. All granulocytic maturation stages expressed L-selectin. The percentage of cells fluorescing increased significantly in BM band and mature granulocytes and reached maximal expression on circulating neutrophils. Bone marrow band and segmented cells showed the highest L-selectin density. Chemotaxis through micropore filters in response to zymosan-activated fetal bovine serum was first observed in the myelocytic and metamyelocytic stages, and it increased with maturation and release into the blood stream. From these results, we conclude that L-selectin expression varies among stages of granulocytic maturation within the BM and differs from circulating PMNL. Further, BM cells are capable of migration starting at the metamyelocytic stage, and compared with BM cells, circulating neutrophils are more chemotactively active.

Animals↗

PubMed2004

Increase of Escherichia coli inoculum doses induces faster innate immune response in primiparous cows.

The objective of the current study was to evaluate the dynamics of infection and the immunological response to varying numbers of Escherichia coli injected into the mammary glands of primiparous cows during the periparturient period. Primiparous cows have been shown to be more resistant to intramammary E. coli challenge, and an increase of the inoculum dose by 2 log10 units induced a more rapid clinical response and clearance of the organisms. Recognition of lipopolysaccharide (LPS) is a key event in the innate immunity response to gram-negative infection and is mediated by the accessory molecules CD14 and LPS-binding protein (LBP). Primiparous cows were inoculated with 1 x 10(4) (Group A; n=8) or 1 x 10(6) (Group B; n=8) cfu E. coli P4:O32 in their 2 left quarters during the periparturient period. Clinical examination and analysis of blood and milk parameters, including IL-8, complement fragment 5a (C5a), LBP, and soluble CD14 (sCD14), were performed from d -4 to d +3 relative to infection. Primiparous cows in Group B initiated a more rapid clinical response following intramammary infection (IMI), resulting in typical clinical signs and changes in blood and milk parameters approximately 3 h earlier compared with primiparous cows in Group A. Based on average milk production in the noninfected quarters on d +2 postinoculation, all heifers reacted as moderate responders. Distinct differences in the kinetic patterns of rectal temperature, somatic cell count (SCC), IL-8, C5a, LBP, and sCD14 were observed between both groups during the early phase of inflammation. Both C5a and IL-8 increased before cellular influx into the infected glands, followed by increases in sCD14 and LBP. In conclusion, primiparous cows are able to clear an intramammary E. coli infection efficiently. Moreover, increasing the inoculum dose induces a more rapid inflammatory reaction, mainly because of early activation of the innate host immune response.

Animals↗

PubMed2004

Viability of milk neutrophils and severity of bovine coliform mastitis.

To study the host-pathogen interactions during Escherichia coli mastitis, we first determined whether E. coli infection would change blood and milk polymorphonuclear neutrophil (PMN) chemiluminescence (CL) and viability. We then hypothesized that when E. coli invade the mammary gland, the viable PMN in milk would efficiently phagocytose and destroy E. coli before establishment of infection. We observed that the phagocytosis-dependent and independent CL were closely linked to PMN viability and were crucial to the outcome of mastitis. Maximal PMN influx and colony-forming units in infected quarters appeared at postinfection hours (PIH) 6 to 24. This further boosted PMN recruitment through bone marrow-blood barrier as well as blood-milk barrier. The survival of recruited PMN in the E. coli-infected quarters was much higher than that of noninfected quarters. Chemiluminescence activity of PMN from the infected quarters significantly increased following E. coli infection, even exceeding that of blood at PIH 6, 12, and 18 to 24; no such increase was observed in noninfected quarters, suggesting that the various responses of milk PMN to stimuli resulted largely from PMN viability. The highest CL intensity and durability was observed in milk PMN from infected quarters at PIH 12. Whereas an increased viability of PMN in the noninfected quarters was only significant at PIH 6, the viability of PMN in infected quarters was long lasting and significantly higher at PIH 6 to 72. Importantly, higher preinfection milk PMN viability correlated with bacterial clearance, which was accompanied by faster recovery. Our study strongly supports the hypothesis that boosting milk PMN viability could be a strategy with which to prevent or reduce the severity of coliform mastitis in dairy cows. This strategy might be achieved through strengthening bone marrow functionality.

Animals↗

PubMed2004

Role of neutrophil polymorphonuclear leukocytes during bovine coliform mastitis: physiology or pathology?

The review compiles some major findings concerning the inflammatory reaction in the mammary gland of dairy cows within the physiological context of the lactation cycle. The dual role of the PMN leukocyte in defense and tissue damage during experimentally induced coliform mastitis, especially around parturition and during early lactation, is highlighted. This disease affects many high producing cows in dairy herds and may cause several cases of death per year in the most severe cases. Most researchers now accept that the PMN is a key factor in the cows' defense against intramammary infection with E coli. During diapedesis of PMN into the mammary gland, several functionally important receptors are up-regulated, allowing for a more efficient phagocytosis and killing of invading pathogens. While PMN are phagocytosing and destroying the invading pathogens, they inadvertently release chemical mediators which induces swelling of secretory epithelium cytoplasm, sloughing of secretory cells, and decreased secretory activity. Permanent scarring will result in a loss of milk production. PMN's act as friends and as foes and are important components in the balance between mammary defense and damage. The mammary gland is a complex open self-regulatory system with a continuous flow of matter, energy and information. Metabolically, it has absolute priority over many other tissues except the brain. Self-regulation with change over time is characterized by a dynamic equilibrium between two mechanisms: homeostatic and homeorhetic. The defense against invaders by innate immunity and auto-repair of the damaged tissues are covered by homeostatic mechanisms while colostrogenesis and maintenance of milk secretion are controlled by mainly homeorhetic mechanisms. However, also innate immunity has to function and develop in time, depending on the lactation cycle, and its behavior and evolution in time in such a dynamical system is a challenge and a problem at the same time. In such a complex dynamic situation it is not surprising that physiology is not far away from pathology. E. coli mastitis can be a severe problem during the beginning of lactation whereas it is completely self-curing after peak lactation (8 weeks). The approach to focus on the PMN doesn't mean that the defense of the mammary gland is more simple than in other tissues. The defense of mammary gland is characterized by its complexity and over the last years many data show that there are tight connections with the mononuclear cells in mammary gland tissue. Today it is known that T cells play a central role in orchestrating the immune response. However, because of the peculiar interest in the PMN of the authors during the last 10 years, the immunobiology of the mononuclear cells in the mammary gland is not covered.

Animals↗