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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Genomics and Improvement Laboratory » Research » Publications at this Location » Publication #311555

Title: The effect of citrus-derived oil on bovine blood neutrophil response in vitro

Author
item GARCIS, M. - University Of Maryland
item Elsasser, Theodore
item BISWAS, D. - University Of Maryland
item MOYES, K. - University Of Maryland

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2014
Publication Date: 4/10/2015
Citation: Garcis, M., Elsasser, T.H., Biswas, D., Moyes, K. 2015. The effect of citrus-derived oil on bovine blood neutrophil response in vitro. Journal of Dairy Science. 98(2):918-926.

Interpretive Summary: Concerns have emerged regarding the potential for antimicrobial drugs to lose effectiveness against infectious pathogens because of the capabilities of some microbes that become resistant to the actions of the drug to proliferate and spread. Consequently there is a large thrust in research towards identifying new compounds that can either replace traditional antibiotics or complement the present use of antibiotic drugs and preserve their efficacy. Oils derived from rind of citrus fruit have been demonstrated to be effective in decontaminating microbes from solid surfaces like countertops. Unrefined citrus oils, however, contain terpenes, a class of compound relatively injurious to delicate cells. If a compound is to be effective as an alternative to a traditional antibiotic drug, not only must it have some level of antimicrobial activity but it also must not be harmful to the immune cells of the host that are also needed to control infection. We determined whether a citrus oil product derived from the rind of Valencia oranges and processed to eliminate terpenes altered the functional capacity of immune cells in the blood (called polymorphonuclear leukocytes). Testing a very low dose (0.01%) in cultured cells, we established that the orange oil did not harm the functions of the cells and, in fact, increased their capability to be called to sites of infection, a process called chemotaxis. The data suggest that low concentrations of Valencia orange oil might be an effective strategy to use in animal diseases like mammary gland infection as an alternative to antibiotic use.

Technical Abstract: Research on the use of natural products to treat or prevent microbial invasion as alternatives to antibiotic use is growing.Polymorphonuclear leukocytes (PMNL) play a vital role with regard to the innate immune response that affects severity and or duration of mastitis. To our knowledge, effect of cold-pressed terpeneless Valencia orange oil (TCO) on bovine PMNL function has not been elucidated. Therefore, the objective of this study was to investigate the effect of TCO on bovine blood PMNL chemotaxis and phagocytosis capabilities and the expression of genes involved in inflammatory response in vitro. Polymorphonuclear leukocytes were isolated from jugular blood of 12 Holstein cows in mid-lactation and were incubated with 0.0 or 0.01% TCO for 120 min at 37ºC and 5% CO2 and phagocytosis (2 × 106 PMNL) and chemotaxis (6 × 106 PMNL) assays were then performed in vitro. For gene expression, RNA was extracted from incubated PMNL (6 × 106 PMNL) and gene expression was analyzed using qPCR. The supernanant was stored at -80ºC for analysis of tumor necrosis factor-a. Data were analyzed using a general linear mixed model with cow and treatment (i.e. control or TCO) in the model statement. In vitro supplementation of 0.01% of TCO increased the chemotactic ability to interleukin-8 by 47%, however, migration of PMNL to complement 5a was not altered. Treatment did not affect the production of tumor necrosis factor-a by PMNL. Expression of pro-inflammatory genes (i.e. SELL, TLR4, IRAK1, TRAF6, and LYZ) coding for proteins were not altered by incubation of PMNL with TCO. However, down-regulation of TLR2 (fold change; FC = treatment/control) = -2.14), NFKBIA (FC = 1.82), IL1B (FC = -2.16), TNFA (FC = -9.43), and SOD2 (FC = -1.57) was observed for PMNL incubated with TCO when compared to controls.Interestingly, expression of IL10, a well known anti-inflammatory cytokine was also down-regulated (FC = -3.78) whereas expression of IL8 (FC = 1.93), a gene coding for the cytokine IL-8 known for its chemotactic function, tended to be up-regulated in PMNL incubated with TCO. Incubation of PMNL with TCO enhanced PMNL chemotaxis in vitro. The expression of genes involved in the inflammatory response was primarily down-regulated. Results showed that 0.01% TCO did not impair the function of PMNL in vitro. Future studies investigating the use of TCO as an alternative therapy for treatment of mastitis, including dose and duration, for cows during lactation are warranted.