ACTH impairs the migratory and secretory profile of mononuclear cells during proestrus in cattle.

The aim was to evaluate the effect of ACTH on the mechanisms involved in peripheral blood mononuclear cells (PBMCs) infiltration into the ovary during dairy cattle proestrus. Regarding this, proper expression pattern of adhesion molecules must take place both in PBMCs and in endothelial cells. Argentinian Holstein cows (n = 12) were treated with 100 IU of ACTH every 12 h for 4 days before ovulation when ovariectomy was performed (day 18). Blood samples were taken on day 15 (0 h) and immediately before (72 h) and after (74 h) the last ACTH administration. In PBMCs, flow cytometry was performed to analyze CD44, CD11b and CD62-L expression along with gene expression of chemokines' receptors. Interleukin (IL)-4 and tumor necrosis factor-α (TNF-α) production was analyzed by flow cytometry after exposing PBMCs to autologous follicular fluid. In ovarian blood vessels, expression of the vascular endothelium cell adhesion-1 (VCAM-1) and the platelet endothelial cell adhesion molecule-1 was evaluated by immunohistochemistry. In T-lymphocytes, the expression of CD44 and CD11b was lower at 72 h in ACTH-treated cows (P < 0.05). In monocytes, the expression of CD11b and CD62-L was lower at 72 h in ACTH-treated cows (P < 0.05). Also, the percentage of IL-4+ cells was higher in ACTH-treated cows, meanwhile, the percentage TNF-α+ cells was lower in ACTH-treated cows (P < 0.05). Finally, in the vessels associated with the preovulatory follicle VCAM-1 immunoexpression was lower in ACTH-treated cows (P < 0.05). Here, we present novel insights into the effect of stress during the preovulatory period on the inflammatory pathway necessary for ovulation.

Association between phagocytic activity of monocytes and days to conception after parturition in dairy cows when considering the hormonal and metabolic milieu.

The nutritional conditions and immune status of dairy cows affect reproductive performance. This study was conducted with the aim to analyze the phagocytic activity (PA) and phagocytic capacity (PC) of circulating monocytes after the period of transition from pregnancy to lactation, to evaluate possible associations with duration of time period to conception following parturition. Results indicated PA was not associated with duration of time period to conception following parturition. In contrast, cows with a lesser PC conceived earlier (98 ± 9 days in milk, DIM) than those with a greater PC (168 ± 15 DIM). Based on these results, to analyze the association of the hormonal and metabolic milieu with the PA and PC, the animals were grouped considering the days to conception following parturition. In the group with the greater number of days to conception (>168 DIM), the PA was associated with concentrations of progesterone and beta-hydroxybutyrate (BHB) at 90 DIM and glucose at 120 DIM, whereas PC was associated with the concentrations of progesterone, cortisol and glucose at 90 DIM, non-esterified fatty acids (NEFA) at 120 DIM, 17ß-estradiol at 150 DIM, and 17ß-estradiol and BHB at 180 DIM. Overall, these results represent a new perspective related to the reproductive performance of dairy cows. The modifications of cellular functions may be useful for predicting the onset of health complications in dairy cows and to manage cows in ways that result in an enhanced fertility during the subsequent lactational period.

Evaluation of the humoral immune response to a multicomponent recombinant vaccine against S. aureus in healthy pregnant heifers.

Staphylococcus aureus is a worldwide pathogen that causes mastitis in dairy herds. Shortcomings in control programs have encouraged the development of vaccines against this pathogen. This study evaluated the vaccine candidate VacR, which included recombinant S. aureus protein clumping factor A (rClf), fibronectin binding protein A (rFnBP) and hemolysin beta (rBt), formulated with a novel immune-stimulating complex. Comparisons were made between healthy pregnant heifers that received either VacR (n=8; VacR group) or phosphate buffered saline (PBS) plus adjuvant (control group) SC in the supramammary lymph node area on days 45 and 15 before the expected calving date. Blood and foremilk samples were collected from 7 to 60days post-calving. After calving, heifers in the VacR group produced higher total IgG (IgGtotal) titers against each component, in both serum (rBt, 3.4×105; rClf, 3.1×105; rFnBP, 2.3×105) and milk (rBt, 2.6×104; rClf, 1.3×104; rFnBP, 1.1×104), than control heifers (P<0.0001). There were increased concentrations of IgG1 and IgG2 in VacR group (P<0.05), in both serum and milk. Humoral responses remained high throughout the period most susceptible to intramammary infections (P<0.01). Antibodies produced against S. aureus rClf and rFnBP reduced bacterial adherence to fibronectin and fibrinogen by 73% and 67%, respectively (P<0.001). Milk antibodies against these adhesins inhibited S. aureus invasion of a mammary epithelial cell line (MAC-T), resulting in 15.7% of bacteria internalized (P<0.0001). There was an approximately 6-fold reduction in the hemolysis titer for the native hemolysin in the VacR group compared to the control group (P<0.0001) and a significantly increase in the proportion of positive neutrophils (VacR, 29.7%; PBS, 13.1%) and the mean fluorescent index (VacR, 217.4; PBS, 152.6; P<0.01) in the VacR group. The results suggest that VacR is a valuable vaccine candidate against S. aureus infections, and merits further field trials and experimental challenges.

Intramammary inoculation of Panax ginseng plays an immunoprotective role in Staphylococcus aureus infection in a murine model.

The immunoprotective effect of Panax ginseng (Pg) extract was investigated in a mouse mastitis model. Lactating female mice were intramammarily inoculated with Pg or placebo, and then were challenged with S. aureus, while other group was inoculated with S. aureus alone. The number of bacteria recovered from mammary glands was significantly lower in Pg-treated S. aureus-infected mice (group I) compared with placebo-treated S. aureus-infected mice (group II) and S. aureus-infected mice (group III). The mRNA expression of TLR2, TLR4, IL-1α and TNF-α was influenced by treatment; being the transcript levels for all genes higher in group I compared with group II and III. Activation of NF-κB and the number of monocytes-macrophages in mammary gland tissue was significantly increased in group I compared with group II and III. Pg extract was able to trigger an adequate immune response to confront an infection demonstrating its protective effect and potential for preventing bovine intramammary infections.

Immune response and functional role of antibodies raised in heifers against a Staphylococcus aureus CP5 lysate and recombinant antigens vaccine formulated with Iscom Matrix adjuvant.

Staphylococcus aureus is the most frequently isolated pathogen from bovine intramammary infections worldwide. Commercially available vaccines for mastitis control are composed either of S. aureus lysates or inactivated whole-cells formulated with traditional adjuvants. We recently showed the ability of a S. aureus CP5 lysate vaccine adjuvanted with Iscom Matrix to generate a longer lasting specific antibody response in blood and milk, with improved opsonic capacity, compared with a S. aureus CP5 whole-cell formulation. The aim of the present study was to obtain an experimental immunogen composed of lysed cells of a CP5 S. aureus strain supplemented with recombinant clumping factor A, fibronectin binding protein A and ß-toxin formulated with Iscom Matrix, characterize the immune response generated when immunizing pregnant heifers and assess the functional role of antibodies raised against this immunogen in experimental models. Both a lysate vaccine and a lysate+recombinant antigens vaccine elicited antibodies that promoted neutrophil phagocytosis and inhibited internalization into mammary epithelial cells, in vitro. Incorporation of defined antigenic molecules to the lysate formulation elicited a strong specific humoral immune response against both lysate and recombinant antigens and was associated with higher expression of regulatory and pro-inflammatory cytokines. In addition, antibodies were efficient for blocking S. aureus binding to bovine fibrinogen and fibronectin, and neutralizing ß-toxin effect in vitro, placing these antigens as candidates to be included in a formulation directed to prevent staphylococcal bovine mastitis.