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1.
OBJECTIVES: To differentiate early (1 to 8 days) from late (9 to 14 days) inflammatory phases and assess relationships between leukocyte phenotype and bacterial recovery in cows with Staphylococcus aureus-induced mastitis. ANIMALS: 10 first-lactation Holstein cows. PROCEDURE: Blood and milk samples were collected from 4 or 6 cows before and after intramammary infusion of sterile broth or S. aureus, respectively. Flow cytometric expression of CD3 and CD11b antigens on blood and milk leukocytes, leukocyte differential counts, bacterial counts in milk, and somatic cell counts were determined longitudinally. RESULTS: Density of CD3 molecules decreased on blood lymphocytes and increased on milk lymphocytes after infusion of bacteria. Density of CD11b molecules on lymphocytes and phagocytes and percentage of CD11b+ lymphocytes in milk increased significantly after infusion; maximum values were achieved during the early inflammatory phase. Density of CD3 and CD11b molecules on milk lymphocytes and macrophages, respectively, 1 day after inoculation were negatively correlated with bacterial recovery on day 1 and days 9 to 14, respectively. Density of CD11b molecules on milk macrophages and the ratios of phagocyte to lymphocyte percentages and polymorphonuclear cell to macrophage percentages in milk differentiated the early from the late inflammatory phase. CONCLUSIONS AND CLINICAL RELEVANCE: Activation of bovine mammary gland macrophages and T cells in response to intramammary infusion of S. aureus was associated with an inability to culture this bacterium from milk. Identification of specific inflammatory phases of S. aureus-induced mastitis in cows may allow for the design of more efficacious treatment and control programs.  相似文献   

2.
The effect of rbGM-CSF intramammary infusion on the subclinical mastitis was evaluated by the somatic cell count (SCC) and expression of adhesion molecules (CD62L and CD11b) on the surface of neutrophils (PMN) in blood and milk. Fifteen cows diagnosed to have subclinical mastitis were used in this study. Seven cows showed a decrease in the SCC (decreased group), whereas 8 cows showed an increase in the SCC (increased group) 7 days after infusion of rbGM-CSF compared to pre infusion level. The percentage of CD62+ cells tended to be lower and CD11b+cells tended to be higher at 6 h on blood PMN in the decreased group of cows. Increased group of cows showed opposite tendencies. The mean fluorescent intensity of these adhesion molecules expressed on PMN in blood and milk was similar in both groups. These results suggested some association between expression of adhesion molecules and changes in SCC by rbGM-CSF. Responsiveness of PMN adhesion molecules to rbGM-CSF might determine the changes in SCC of the subclinical mastitic cows after infusion of rbGM-CSF.  相似文献   

3.
OBJECTIVE: To determine whether apoptosis of neutrophils was accelerated during mastits experimentally induced by use of Escherichia coli or E coli endotoxin and whether differences were apparent in the response to E coli or endotoxin. ANIMALS: 11 healthy lactating Holstein cows. PROCEDURE: Blood samples were collected from cows at various intervals after intramammary inoculation with E coli or endotoxin. Percentage of apoptotic neutrophils detected after in vitro incubation for 3 hours was determined. Fluorescein isothiocyanate-labeled annexin-V in combination with propidium iodide was used to distinguish apoptosis and necrosis of neutrophils. Total and differential circulating leukocyte counts and rectal temperature were determined at the time of collection of blood samples. Milk yield and milk somatic cell counts were determined at the time of milking. RESULTS: Inoculation of endotoxin did not accelerate in vitro induction of neutrophil apoptosis. However, inoculation of E coli increased the percentage of apoptotic neutrophils. At 18 hours after inoculation, 20% of the neutrophils were apoptotic, compared with 5% before inoculation. Milk somatic cell count and rectal temperature increased, milk production and total leukocyte count decreased, and percentage of immature neutrophils increased after inoculation with E coli or endotoxin. However, kinetics of the responses were more rapid, more severe, and of shorter duration during endotoxin-induced mastitis. CONCLUSIONS AND CLINICAL RELEVANCE: In vitro induction of apoptosis of neutrophils was accelerated only during E coli-induced mastitis and not during endotoxin-induced mastitis. Endotoxin inoculation as a model for studying coliform mastitis in dairy cows should be viewed with caution.  相似文献   

4.

Blood neutrophils use CD62L and CD18 adhesion molecules to contact and migrate rapidly through blood vessels in defense against infections in underlying tissues. Previous work showed that glucocorticoid hormones repress expression of CD62L and CD18, causing neutrophilia and increased mastitis susceptibility in dairy cows. The aim of this study was to determine whether bovine neutrophil sensitivity to glucocorticoids exhibits genetic variability. Test animals included 60 pedigreed Holstein bulls treated on 3 consecutive days with a synthetic glucocorticoid (dexamethasone) and five untreated control bulls. Five indicator traits of neutrophil glucocorticoid sensitivity were monitored, including circulating neutrophil counts and two measures on each of CD62L and CD18 expression. Random regression models with treatment-specific serial correlation were used to estimate genetic and non-genetic sources of variation before, during and after glucocorticoid administration. Significant genetic variation was observed for neutrophil CD18 expression, with longitudinal heritability estimates ranging from 0.10 to 0.54 and influenced by dexamethasone. Significant genetic variation was also observed for blood neutrophil counts (heritability estimates ranging from 0.11 to 0.24) but was not influenced by dexamethasone administration. Estimated genetic correlations between circulating neutrophil counts and various indicators of CD62L and CD18 expression were large and negative (-0.44 to - 0.78). These results imply significant genetic variability and pleiotropic effects for neutrophil traits that are important for stress-induced disease susceptibility in dairy cattle and might be exploited by genetic selection.  相似文献   

5.
OBJECTIVE: To determine whether proinflammatory mediators and glucocorticoids affect CD62L(L-selectin) expression on peripheral blood neutrophils from cows in various stages of lactation. ANIMALS: 100 healthy dairy cows during early (13.1 +/- 0.79 days after parturition; n = 31), peak (58.7 +/- 1.64 days after parturition; 31), and mid (137.2 +/- 2.59 days after parturition; 38) lactation. PROCEDURE: In vitro effects of relevant proinflammatory mediators that are released in response to mastitis caused by gram-negative bacteria such as lipopolysaccharide (endotoxin), tumor necrosis factor-alpha, and platelet-activating factor (PAF) on CD62L expression on bovine neutrophils were assessed by flow cytometry. Influences of cortisol and dexamethasone on CD62L expression on bovine neutrophils were also investigated. RESULTS: Basal CD62L expression on neutrophils from cows during early, peak, and mid lactation were similar. Lipopolysaccharide and tumor necrosis factor-alpha had no effect on CD62L expression on neutrophils from cows at any stage of lactation. Conversely, PAF elicited a time- and dose-dependent, down regulatory effect on CD62L expression. However, no differential shedding of CD62L from neutrophils of cows at any stage of lactation were detected. In addition, no effects on CD62L expression on bovine neutrophils after whole blood incubation with cortisol or dexamethasone were observed. Incubation with glucocorticoids did not prevent the down regulatory effect of PAF on CD62L expression. CONCLUSIONS AND CLINICAL RELEVANCE: Comparable basal CD62L expression on bovine neutrophils and equal amounts of CD62L shedding from bovine neutrophils during all stages of lactation suggest that variations in CD62L density are not a likely cause of susceptibility of cows to coliform-induced mastitis during early lactation.  相似文献   

6.
L-selectin (CD62L) gene expression in neutrophils is commonly referred to as "constitutive" because circulating neutrophils require a constant supply of this adhesion molecule for continuous trafficking into peripheral tissues. Under normal circumstances, marginating blood neutrophils and neutrophils that become activated for migration into infected tissues rapidly shed surface CD62L that is ligated to the vascular endothelium. However, this does not shut down CD62L gene expression because these cells continue to express surface CD62L. In contrast, glucocorticoid challenges resulting from stress and hormone injections result in gradual and chronic down-regulation of CD62L on the surface of blood neutrophils. Rather than being associated with migration, this type of CD62L down-regulation associates with pronounced neutrophilia and increased susceptibility to infections. Nothing is currently known about glucocorticoid regulation of CD62L expression in neutrophils. In other cell systems, however, this steroid hormone binds to cytoplasmic glucocorticoid receptors (GR) that influence expression of glucocorticoid-responsive genes at multiple pre-translational levels. Thus, the hypothesis of the present study was that glucocorticoid challenge suppresses CD62L mRNA expression in blood neutrophils. Suppressed CD62L gene expression might help explain the chronic down-regulation of surface CD62L in neutrophils and accompanying neutrophilia. The main objectives of the study were to monitor neutrophil CD62L mRNA abundance before and during subtle and severe glucocorticoid challenges and to determine if CD62L mRNA expression correlates with degree of glucocorticoid challenge. Parturient dairy cows and dexamethasone-treated steers were used as models of subtle and severe (respectively) glucocorticoid challenges. Data presented from both models support the hypothesis and show for the first time that glucocorticoids regulate neutrophil CD62L at a pre-translational level. Results also showed that inhibited CD62L mRNA expression correlated precisely with down-regulated surface expression of CD62L on neutrophils and peak neutrophilia during severe glucocorticoid challenge. Therefore, results of this study indicate that bovine neutrophils are highly sensitive to the blood environment, displaying full capacity to alter CD62L gene expression and trafficking patterns in response to changing glucocorticoid levels. This may serve animals well when heightened inflammatory responses begin to lead to tissue damage, but may be detrimental to overall health if animals are exposed to opportunistic pathogens while stressed or undergoing glucocorticoid therapy. Although this study did not elucidate how glucocorticoids inhibit neutrophil CD62L mRNA expression, presented data implicate GR as possibly being involved because neutrophils from cattle in both models expressed GR mRNA. Further in vitro studies using purified populations of neutrophils will be required to determine if GR is directly involved in glucocorticoid regulation of CD62L gene expression and, if so, at what level.  相似文献   

7.
OBJECTIVES: To determine the structural and functional alterations in circulating neutrophils that may lead to sequestration in lung microvasculature and endothelial injury in calves with experimentally induced pneumonic pasteurellosis. ANIMALS: 10 healthy, 2- to 4-week-old male Holstein calves. PROCEDURES: Holstein calves were anesthetized and inoculated intrabronchially with Dulbecco phosphate buffered saline (0.9% NaCl) solution (DPBSS; 5 control calves) or 1 x 10(9) Pasteurella haemolytica organisms (5 infected calves). Blood samples were collected before and 1, 2, 4, and 6 hours after inoculation. Total and differential WBC count, dilute whole blood leukocyte deformability, neutrophil size distribution, and neutrophil surface CD11b expression were measured in blood samples. RESULTS: A progressive decrease in leukocyte deformability and increase in neutrophil size was detected 1, 2, 4, and 6 hours after inoculation of P haemolytica. Neutrophil surface CD11b expression was greater than baseline values at 6 hours after inoculation of P haemolytica. Two populations of neutrophils with an increase in size were detected in P haemolytica-infected calves. Both subpopulations had increased CD11b expression, compared with neutrophils that were typical in size. CONCLUSIONS AND CLINICAL RELEVANCE: Neutrophils circulate in an activated and nondeformable state in calves with experimentally induced pneumonic pasteurellosis. A decrease in neutrophil deformability and neutrophil aggregation may contribute to neutrophil trapping in the lung microvasculature during pneumonic pasteurellosis in calves.  相似文献   

8.
In the period around parturition, cows experience an increased susceptibility for the development of Escherichia coli mastitis. This increased susceptibility has been correlated with a decreased functionality of neutrophils. In the current study, it is suggested that the decreased neutrophil functionality may be induced by the extensive alterations in sex steroid levels occurring around parturition. It was first hypothesized that 17beta-estradiol and progesterone influence the viability, apoptosis and necrosis of blood neutrophils from cows in their last month of gestation. Subsequently, it was hypothesized that 17beta-estradiol modulates the expression of CD11b, CD18 or CD47 thereby explaining its influence on the migration of bovine neutrophils. Neither 17beta-estradiol nor progesterone significantly influenced viability, apoptosis or necrosis in spontaneous apoptosis conditions. However, when apoptosis was induced with TNF-alpha and gliotoxin, progesterone exerted a survival effect (P<0.05). In addition, 17beta-estradiol treatment of bovine blood neutrophils significantly decreased the expression of CD47 (P<0.05) but not of CD11b or CD18. It can be concluded that 17beta-estradiol and progesterone do not affect spontaneous apoptosis of bovine blood neutrophils while a survival effect was observed for progesterone on induced neutrophils apoptosis. Moreover, our results concerning the influence of 17beta-estradiol on the CD11b, CD18 and CD47 expression extend previous demonstrations of the suppressive effect of 17beta-estradiol on neutrophils migration and indicate that the altered expression of CD47 may contribute to this phenomenon.  相似文献   

9.
OBJECTIVE: To determine the effect of mastitis caused by Escherichia coli on expression of CD18 cell surface receptors and to evaluate the involvement and regulation of receptors by lipopolysaccharide (LPS) and cortisol. ANIMALS: 11 clinically normal lactating Holstein-Friesian cows. PROCEDURE: Binding of CD18 monoclonal antibodies to neutrophils was studied, using flow cytometry, before and after intramammary inoculation of E. coli organisms. Effect of LPS and cortisol on expression of adhesion receptors was investigated, using a whole-blood model. RESULTS: Expression of CD18 adhesion receptors on bovine neutrophils increased 35% by 12 hours after intramammary inoculation of E. coli. By 24 hours after inoculation, the number of receptors had returned to control values. High cortisol concentrations (100 nmol/L) were seen 12 to 18 hours after inoculation. Addition of LPS to blood induced a 30% increase in the number of CD18 receptors, and maximal number of receptors was expressed at an LPS concentration of 0.1 ng/ml. A decrease in the number of CD18 receptors was induced by incubation with cortisol or dexamethasone before challenge-exposure with LPS. CONCLUSIONS: An increase in the number of CD18 receptors on neutrophils is mediated by local production of LPS. Subsequent endogenous release of cortisol may prevent additional increases in the number of receptors. CLINICAL RELEVANCE: During acute mastitis caused by E. coli, there is an increase in the number of CD18 receptors on circulating neutrophils. Cortisol induces a decrease in the number of CD18 receptors, probably modulating the acute inflammatory response in mammary glands of lactating cows.  相似文献   

10.
This study was undertaken to investigate the time course of surface expression of CD14 on neutrophils and macrophages and to determine their association with resolution of inflammatory responses during Staphylococcus aureus and Streptococcus uberis experimental mastitis. Infections of the mammary gland induce a local immune response characterized by an increase in the total counts of CD14+ neutrophils and CD14+ macrophages particularly. On the other hand, resolution is accompanied by an increase in relative counts of CD14+ neutrophils, CD14+ vacuolized macrophages and apoptotic neutrophils. Following the immune reaction of mammary gland against Gram-negative/positive bacteria is very similar. Between the apoptotic and CD14+ neutrophils a high correlation was measured during the whole experimental period (S. aureus: r=0.64; S. uberis: r=0.61; P<0.05). Using anti-CD14 monoclonal antibodies in vitro suggested the involving of the CD14 surface receptor in recognition of apoptotic neutrophils by macrophages.  相似文献   

11.
Dairy cows are highly susceptible to infectious diseases, like mastitis, during the period around calving. Although factors contributing to increased susceptibility to infection have not been fully elucidated, impaired neutrophil recruitment to the site of infection and changes in the concentrations of some micronutrients related with the function of the immune defence has been implicated. Most of the current information is based on studies outside the Nordic countries where the conditions for dairy cows are different. Therefore, the aim of the study was to evaluate changes in blood concentrations of the vitamins A and E, the minerals calcium (Ca), phosphorous (P), and magnesium (Mg), the electrolytes potassium (K) and sodium (Na) and the trace elements selenium (Se), copper (Cu) and zinc (Zn), as well as changes in total and differential white blood cell counts (WBC) and expression of the adhesion molecules CD62L and CD18 on blood neutrophils in Swedish dairy cows during the period around calving. Blood samples were taken from 10 cows one month before expected calving, at calving and one month after calving. The results were mainly in line with reports from other countries. The concentrations of vitamins A and E, and of Zn, Ca and P decreased significantly at calving, while Se, Cu, and Na increased. Leukocytosis was detected at calving, mainly explained by neutrophilia, but also by monocytosis. The numbers of lymphocytes tended to decrease at the same time. The mean fluorescent intensity (MFI) of CD62L and CD18 molecules on blood neutrophils remained constant over time. The proportion of CD62L+ neutrophils decreased significantly at calving. The animals were fed according to, or above, their requirements. Therefore, changes in blood levels of vitamins, minerals and trace elements were mainly in response to colostrum formation, changes in dry matter intake, and ruminal metabolism around calving. Decreased levels of vitamins A and E, and of Zn at calving might have negative implications for the functions of the immune defence. The lower proportion of CD62L+ neutrophils at calving may result in less migration of blood neutrophils into the tissues, and might contribute to the increased susceptibility to infections at this time.  相似文献   

12.
Staphylococcus aureus is a major pathogen associated with mastitis, a disease affecting both women and dairy cows. The longitudinal profiles of bovine peripheral blood and mammary gland lymphocyte phenotypes in response to S. aureus-induced mastitis were investigated in dairy cows. Increased percentage of CD4 lymphocytes in the mammary gland between 1 and 8 days post-inoculation, increased milk CD4 protein density per cell between 1-8 days post-inoculation, and a statistically significant negative correlation between post-inoculation bacterial counts in milk and blood lymphocyte CD4 protein density were found. Together with blood and milk leukocyte counts, the milk lymphocyte CD4/CD8 ratio and the milk lymphocyte CD4 protein density were more informative indicators than milk somatic cell counts and bacteriology for identification of early vs. late inflammatory phases. These findings suggest that CD4+ lymphocytes play a protective role in the early stages of S. aureus-induced mastitis.  相似文献   

13.
The responses of five lactating ewes to experimental mammary infection with Staphylococcus epidermidis were examined. Infection caused an intense but transient influx of neutrophils into milk, which peaked at 8 h and was accompanied by mild fever and mild leukopaenia in blood. No other signs of systemic infection were observed. Number of staphylococci in milk decreased logarithmically until 24 h, were absent from three ewes at 48 h and then increased in number or re-emerged in four of the five ewes at 72 or 144 h. At all times milk appeared grossly normal. Expression of the adhesion molecules CD11b and CD18 increased on neutrophils in milk at 24 h then tended to decline over subsequent days. The proportion of lymphocytes positive for CD4, CD8, WC1 and MHCII tended to decrease from 24 to 72 h then increased at 144 h. Cytokines in milk were measured by ELISA. IL-8 was elevated in infected glands at 2 h, peaked at 24 h and remained elevated until the final sampling at 144 h. IL-6 was transiently elevated at 4 and 8 h while IL-1beta remained elevated from 8 until 144 h. The results suggest that the intense early neutrophil infiltrate eliminated most but not all bacteria and a state of subclinical infection ensued. After 24 h , leukocyte numbers in milk declined while cytokines, especially IL-8 remained elevated, suggesting that sensitivity or responsiveness of gland to inflammatory signals decreased as infection progressed. This attenuation of the host defence response may have contributed to the failure of the gland to eliminate bacteria and may be an important feature of the development of chronic and subclinical mastitis.  相似文献   

14.
OBJECTIVE: To investigate rheologic properties of bovine neutrophils that may result in adhesion molecule-independent sequestration of neutrophils in inflamed lungs of cattle. ANIMALS: Healthy 2- to 4-week-old male Holstein calves. PROCEDURES: Neutrophil deformability, filamentous actin (F-actin) content, and CD11b expression was determined for unstimulated bovine neutrophils and bovine neutrophils incubated with the inflammatory mediators tumor necrosis factor-alpha (TNF), platelet-activating factor (PAF), interleukin-8 (IL-8), zymosan-activated plasma (ZAP), Pasteurella haemolytica-derived lipopolysaccharide (LPS), and P haemolytica leukotoxin. Neutrophils were separated into 3 subpopulations on the basis of size. The Factin content and CD11 b expression were evaluated by use of flow cytometry. Leukocyte deformability was evaluated by filtration of dilute whole blood. RESULTS: The subpopulation of the smallest-sized neutrophils (>90% of neutrophils) contained little F-actin. A subpopulation of slightly larger neutrophils had a profound increase in F-actin content and CD11 b expression. The subpopulation of the largest neutrophils had increased F-actin content and CD11b expression, compared with those for both subpopulations of smaller neutrophils. Incubation of neutrophils with PAF and ZAP but not TNF, IL-8, LPS, or leukotoxin, resulted in decreased neutrophil deformability and increased F-actin content. Incubation with PAF and TNF induced an increase in size of neutrophils. CONCLUSIONS AND CLINICAL RELEVANCE: Size can be used to identify subpopulations of large and rigid neutrophils in blood samples from healthy calves. Platelet-activating factor and activated complement fragments are potent inducers of F-actin formation and neutrophil rigidity. Physical changes in neutrophils may impede their transit through lung microvasculature and result in leukocyte trapping independent of adhesion molecule interactions with endothelial cells.  相似文献   

15.
D-lactic acidosis occurs in ruminants, such as cattle, with acute ruminal acidosis caused by ingestion of excessive amounts of highly fermentable carbohydrates. Affected animals show clinical signs similar to those of septic shock, as well as acute laminitis and liver abscesses. It has been proposed that the inflammatory response and susceptibility to infection could both be caused by the inhibition of phagocytic mechanisms. To determine the effects of d-lactic acid on bovine neutrophil functions, we pretreated cells with different concentrations of D-lactic acid and measured intracellular pH using 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM) and calcium flux using FLUO-3 AM-loaded neutrophils. Reactive oxygen species (ROS) production was measured using a luminol chemiluminescence assay, and MMP-9/gelatinase-B granule release was measured by zymography. CD11b and CD62L/l-selectin expression, changes in cell shape, superoxide anion production, phagocytosis of Escherichia coli-Texas red bioparticles, and apoptosis were all measured using flow cytometry. Our results demonstrated that D-lactic acid reduced ROS production, CD11b upregulation and MMP-9 release in bovine neutrophils treated with 100 nM platelet-activating factor (PAF). D-lactic acid induced MMP-9 release and, at higher concentrations, upregulated CD11b expression, decrease L-selectin expression, and induces late apoptosis. We concluded that D-lactic acid can interfere with neutrophil functions induced by PAF, leading to reduced innate immune responses during bacterial infections. Moreover, the increase of MMP-9 release and CD11b expression induced by 10mM D-lactic acid could promote an nonspecific neutrophil-dependent inflammatory reaction in cattle with acute ruminal acidosis.  相似文献   

16.
OBJECTIVE: To determine the capacity of inflammatory mediators tumor necrosis factor-alpha (TNF-alpha), interleukin-8 (IL-8), platelet-activating factor (PAF), lipopolysaccharide (LPS), and leukotoxin to prime, activate, or alter deformability of adult bovine neutrophils. SAMPLE POPULATION: Blood collected from 5 healthy adult Holstein cows. PROCEDURE: Isolated neutrophils or whole blood was incubated with TNF-alpha, IL-8, PAF, LPS, or leukotoxin, and neutrophil chemiluminescence, degranulation, deformability, shape change, CD11b expression, and size distribution was measured. RESULTS: Incubation with TNF-alpha, IL-8, PAF, and LPS primed neutrophils for oxygen radical release but caused minimal oxygen radical release by themselves. None of the inflammatory mediators induced degranulation. Incubation with TNF-alpha and PAF resulted in a decrease in neutrophil deformability and induced shape change in neutrophils. Incubation with PAF consistently resulted in an increase in neutrophil size as measured by use of flow cytometry. Only IL-8 caused an increase in expression of CD11b by neutrophils. CONCLUSIONS AND CLINICAL RELEVANCE: Inflammatory mediators tested had minimal effects on neutrophil oxygen radical production or degranulation but did prime neutrophils for oxygen radical production. Incubation with PAF and TNF-alpha caused a decrease in neutrophil deformability and altered neutrophil shape and size. Results of our study indicate that PAF- and TNF-alpha-induced changes in neutrophil deformability and size may cause integrin- and selectin-independent trapping of neutrophils in the lungs of cattle with pneumonic pasteurellosis.  相似文献   

17.
OBJECTIVE: To determine whether platelet-activating factor (PAF) is involved in acute lung microvascular injury associated with pneumonic pasteurellosis in calves. ANIMALS: 15 healthy 2- to 4-week-old male Holstein calves. PROCEDURE: Calves were anesthetized and inoculated intrabronchially with saline (0.9% NaCl) solution (n = 5) or 1x10(9) Pasteurella haemolytica organisms (n = 10). Of the 10 calves inoculated with P haemolytica, 5 also were treated with WEB 2086, a potent inhibitor of PAF, and 5 were treated with vehicle. Blood and bronchoalveolar lavage samples were collected before and 1, 2, 4, and 6 hours after inoculation of P. haemolytica. Blood samples were analyzed to evaluate total number and differential counts of leukocytes, dilute whole-blood leukocyte deformability, size of neutrophils, and neutrophil CD11b expression. Bronchoalveolar lavage samples were analyzed for total number and differential counts of nucleated cells, total protein concentration, and hemoglobin concentration. Size and gross and histologic appearance of lung lesions also was determined. RESULTS: Treatment of calves with WEB 2086 reduced size of lung lesions, attenuated the increase in microvascular permeability, and reduced neutrophil infiltration in the first 4 hours after inoculation. Treatment with WEB 2086 also attenuated a decrease in leukocyte deformability, increase in size of neutrophils, and CD11b expression by circulating neutrophils. CONCLUSIONS AND CLINICAL RELEVANCE: It appears that PAF is a major mediator for altered lung microvascular permeability and activation of circulating neutrophils in the first 4 hours after onset of pneumonic pasteurellosis in calves.  相似文献   

18.
OBJECTIVE: To determine effects of parturition on glucocorticoid receptor (GR) expression in neutrophils, serum cortisol concentration, and total blood leukocyte and neutrophil counts in periparturient dairy cows. ANIMALS: 23 Holstein cows. PROCEDURE: Blood samples were collected from 8 multiparous and 5 primiparous periparturient cows at various times from 28 days before parturition until 14 days after parturition. Glucocorticoid receptor expression in neutrophils, serum cortisol concentration, and total blood leukocyte and neutrophil counts were determined. Results were compared with results from control samples obtained from 5 multiparous and 5 primiparous Holstein cows in midpregnancy. RESULTS: Neutrophils from periparturient cows had 49% reduction in GR expression at calving, compared with GR expression 2 to 4 weeks before calving, and 39% reduction, compared with neutrophils from cows in midpregnancy. Reduction in neutrophil GR expression began 1 week before calving and was most severe at calving and 24 hours after calving; a significant difference in GR expression was detected between primiparous and multiparous cows. Serum cortisol concentrations and total leukocyte and neutrophil counts were significantly increased at calving and returned to baseline values by 24 hours after calving. Significant negative correlations were detected between neutrophil GR expression and serum cortisol concentration, total leukocyte count, and neutrophil count. CONCLUSIONS AND CLINICAL RELEVANCE: Reduced GR expression in blood neutrophils of periparturient dairy cows was associated with increased serum cortisol concentrations, leukocytosis, and neutrophilia. Thus, GR down-regulation in neutrophils may be involved in periparturient neutrophil dysregulation and may cause increased susceptibility to mastitis.  相似文献   

19.
Mastitis, inflammation of the mammary gland, is a common and economically important disease in dairy animals. Mammary pathogenic organisms, such as Escherichia coli, invade the teat canal,milk ducts, and mammary alveolar space, replicate in mammary secretions, and elicit a local inflammatory response characterized by massive recruitment of blood polymorphonuclear neutrophil leukocytes (PMN) into the alveoli and milk ducts. CD44 is a trans-membrane glycoprotein previously shown to play a role in mediation and control of blood PMN recruitment in response to inflammatory signals. Here we show, for the first time, increased expression of CD44 on recruited milk PMN in bovine mastitis and the expression of a CD44 variant, CD44v10, on these PMN. Furthermore, we demonstrate that CD44 mediates specific adhesion of bovine blood PMN to hyaluronic acid and mammary epithelial cells. Our results suggest that in mastitis CD44 plays a role in recruiting blood PMN into the mammary glands, the exact nature of this role needs to be elucidated.  相似文献   

20.
The aim of this study was to investigate the importance of bacterial growth for the severity of experimental Escherichia coli mastitis, indirectly expressed as the area under the curve of bacterial counts in milk over time. The association of pre-infusion somatic cell count and post-infusion influx of inflammatory cells in milk with severity of infection was also examined. Bacterial growth was studied through culture in milk samples (in vitro) and through monitoring of bacterial counts in milk during the early phase of infection (in vivo) in 36 cows. Individual variation in bacterial counts was more than 2 x 10(2)-fold after 6 h of in vitro incubation, and more than 8 x 10(2)-fold 6 h after intramammary infusion. In vitro growth in milk was not associated with in vivo growth during the early phase of infection, nor with severity of E. coli mastitis. Somatic cell count before experimental E. coli mastitis was negatively associated with in vivo bacterial growth during the early phase of infection (R2 = 0.28), but was not associated with severity of E. coli mastitis (R2 = 0.06). In vivo bacterial growth during the early phase of infection (positive association; R2 = 0.41), together with influx of inflammatory cells in milk, expressed as mean hourly increase of somatic cell count between 6 and 12 h post-infusion (negative association; R2 = 0.11), are major determinants for the severity of experimental E. coli mastitis (R2 = 0.56).  相似文献   

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