Milk Macrophage Function in Bovine Leukemia Virus-Infected Dairy Cows

The BLV-miRNAs pathway of BLV inhibits the expression of Lactoferrin, Lactoperoxidase, Alpha-lactalbumin and Beta-lactoglobulin proteins

Bovine leukemia virus (BLV) is a widespread virus that decreases milk production and quality in dairy cows. As crucial components of BLV, BLV-encoded microRNAs (BLV-miRNAs) affect BLV replication and may impact the synthesis of Lactoferrin (LTF), Lactoperoxidase (LPO), Alpha-lactalbumin (alpha-LA), and Beta-lactoglobulin (beta-LG). In this study, we investigated the targeting relationship between BLV-miRNAs and LTF, LPO, alpha-LA, and beta-LG in cow's milk. Additionally, we investigated the possible mechanisms by which BLV reduces milk quality. The results showed that cow's milk had significantly lower levels of LTF, LPO, and alpha-LA proteins in BLV-positive cows than in BLV-negative cows. BLV-△miRNAs (miRNA-deleted BLV) enhanced the reduction of LPO, alpha-LA, and beta-LG protein levels caused by BLV infection. Multiple BLV-miRNAs have binding sites with LTF and LPO mRNA; however, only BLV-miR-B1-5 P has a targeting relationship with LPO mRNA. The results revealed that BLV-miR-B1-5 P inhibits LPO protein expression by targeting LPO mRNA. However, BLV does not directly regulate the expression of LTF, alpha-LA, or beta-LG proteins through BLV-miRNAs.

Lycopene promoted M2 macrophage polarization via inhibition of NOTCH1-PI3K-mTOR-NF-κB-JMJD3-IRF4 pathway in response to Escherichia coli infection in J744A.1 cells

Escherichia coli (E. coli) can induce severe clinical bovine mastitis, which is to blame for large losses experienced by dairy farms. Macrophage polarization into various states is in response to pathogen infections. Lycopene, a naturally occurring hydrocarbon carotenoid, relieved inflammation by controlling M1/M2 status of macrophages. Thus, we wanted to explore the effect of lycopene on polarization states of macrophages in E. coli-induced mastitis. Macrophages were cultivated with lycopene for 24, before E. coli inoculation for 6 h. Lycopene (0.5 μmol/L) significantly enhanced cell viabilities and significantly reduced lactic dehydrogenase (LDH) levels in macrophages, whereas 2 and 3 μmol/L lycopene significantly enhanced LDH activities. Lycopene treatment significantly reduced the increase in LDH release, iNOS, CD86, TNF-α, IL-1β and phosphatase and tensin homolog (PTEN) expressions in E. coli group. 0.5 μmol/L lycopene significantly increased E. coli-induced downregulation of CD206, arginase I (ARG1), indoleamine 2,3-dioxygenase (IDO), chitinase 3-like 3 (YM1), PI3K, AKT, p-AKT, mammalian target of rapamycin (mTOR), p-mTOR, jumonji domain-containing protein-3 (JMJD3) and interferon regulatory factor 4 (IRF4) levels. Moreover, Ginkgolic acid C17:1 (a specific PTEN inhibitor), 740YPDGFR (a specific PI3K activator), SC79 (a specific AKT activator) or CHPG sodium salt (a specific NF-κB activator) significantly decreased CD206, AGR1, IDO and YM1 expressions in lycopene and E. coli-treated macrophages. Therefore, lycopene increased M2 macrophages via inhibiting NOTCH1-PI3K-mTOR-NF-κB-JMJD3-IRF4 pathway in response to E. coli infection in macrophages. These results contribute to revealing the pathogenesis of E. coli-caused bovine mastitis, providing the new angle of the prevention and management of mastitis.

BLV-miR-B1-5p Promotes Staphylococcus aureus Adhesion to Mammary Epithelial Cells by Targeting MUC1

Bovine leukemia virus (BLV) is widely prevalent worldwide and can persistently infect mammary epithelial cells in dairy cows, leading to reduced cellular antimicrobial capacity. BLV-encoded microRNAs (BLV-miRNAs) can modify host genes and promote BLV replication. We previously showed that BLV-miR-B1-5p significantly promoted Staphylococcus aureus (S. aureus) adhesion to bovine mammary epithelial (MAC-T) cells; however, the pathway responsible for this effect remained unclear. This study aims to examine how BLV-miR-B1-5p promotes S. aureus adhesion to MAC-T cells via miRNA target gene prediction and validation. Target site prediction showed that BLV-miR-B1-5p could target the mucin family gene mucin 1 (MUC1). Real-time polymerase chain reaction, immunofluorescence, and dual luciferase reporter assay further confirmed that BLV-miR-B1-5p could target and inhibit the expression of MUC1 in bovine MAC-T cells while interfering with the expression of MUC1 promoted S. aureus adhesion to MAC-T cells. These results indicate that BLV-miR-B1-5p promotes S. aureus adhesion to mammary epithelial cells by targeting MUC1.

Genetic polymorphism of prolactin and nitric oxide synthase in Holstein cattle

Background and Aim

Bacterial and viral infections affect the welfare of animals and lead to large economic losses in dairy cattle breeding due to decreased productive indicators and increased culling rates. In modern dairy farming, farmers are looking for effective solutions to prevent and minimize infectious disease risks. To this end, the most relevant study field is the search for gene sites that impact production and health. This study aimed to determine the nature of the distribution of the relative frequencies of alleles and genotypes of polymorphic prolactin (PRL) and nitric oxide synthase (NOS2) in Holstein cows and identify the relationship of these genes with resistance to mastitis and bovine leukemia.

Materials and Methods

For this study, we chose cows because infectious diseases affect the amount of lactation and milk quality. Holstein cattle with mastitis and bovine leukemia were selected. Animal genotypes were determined by restriction fragment length polymorphism (RFLP) of polymerase chain reaction (PCR) products. The results were analyzed using a nonparametric statistical method using Microsoft Excel 2010 and Statistica 6.0.

Results

In healthy animals, 94 genotypes were identified for both genes under study. For bPRL, bPRL-RsaI^AA (72) was the most common genotype and bPRL-RsaI^BB (4) the least; for NOS2, bNOS2 -HinfI^AB (47) was the most common genotype and bNOS2 -HinfI^AA the least (21). In animals with leukemia, 34 genotypes were identified. For PRL, bPRL-RsaI^AA (25) was the most common genotype and bPRL-RsaI^BB (2) the least; for NOS2, bNOS2 -HinfI^BB (17) was the most common genotype and bNOS2 -HinfI^AA (3) the least. In animals with mastitis, 67 genotypes were identified. For PRL, bPRL-RsaI^AA (43) was the most common genotype and bPRL-RsaI^BB (6) the least; for NOS2, bNOS2 -HinfI^BB (31) was the most common genotype and bNOS2-HinfI^AA (7) the least. The distribution of genotypes of polymorphic bPRL and bNOS2 generally coincides, and bPRL-RsaI^BB is the most common genotype. In groups of sick animals, the number of bNOS2 -HinfI^AA homozygotes was lower than that of the control group. In particular, the proportion of animals with the bNOS2 -HinfI^AA genotype with bovine leukemia was 8.7% and with mastitis was 10.3% compared with 22.4% in healthy animals. These data support the possible association of the bNOS2 -HinfI^AA genotype with resistance to infection. The frequency of the bPRL-RsaI^B allele was higher in groups of sick animals. This allele is associated with increased milk productivity, suggesting that highly productive animals are less resistant to the incidence of viral bovine leukemia and mastitis of bacterial etiology.

Conclusion

DNA amplification of Holstein cattle for the polymorphic regions of PRL and NOS2 using the PCR-RFLP method revealed a possible connection between the distribution of relative allele frequencies of bPRL and bNOS2 and resistance to viral and bacterial infections. Thus, in groups of sick animals, the frequency of bPRL-RsaI^BB, associated with increased milk production compared with the theoretically calculated equilibrium value was higher and the number of homozygotes bNOS2 -HinfI^AA was lower than in the control group. In conclusion, animals with increased milk production were more prone to diseases, such as mastitis and bovine leukemia.

Milk lymphocyte profile and macrophage functions: new insights into the immunity of the mammary gland in quarters infected with Corynebacterium bovis

BACKGROUNDS

The present study explored the viability of bovine milk macrophages, their intracellular production of reactive oxygen and nitrogen species (RONS), and their phagocytosis of Staphylococcus aureus, as well as the profile of lymphocytes, from healthy udder quarters and udder quarters infected by Corynebacterium bovis. The study included 28 healthy udder quarters from 12 dairy cows and 20 udder quarters infected by C. bovis from 10 dairy cows. The percentages of macrophages and lymphocytes were identified by flow cytometry using monoclonal antibodies. Macrophage viability, RONS production, and S. aureus phagocytosis were evaluated by flow cytometry.

RESULTS

Milk samples from quarters infected with C. bovis showed a lower percentage of macrophages but an increased number of milk macrophages per mL and a higher percentage of macrophages that produced intracellular RONS and phagocytosed S. aureus. No effect of C. bovis infection on macrophage viability was found. Udder quarters infected by C. bovis showed a higher percentage of T cells and CD4+ T lymphocytes, but no effect was found on the percentage of CD8+ CD4- T, CD8- CD4- T, or B lymphocytes.

CONCLUSIONS

Thus, our results corroborate, at least in part, the finding that intramammary infections by C. bovis may offer protection against intramammary infections by major pathogens.