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Title:Effects of plant extracts on immune function and disease resistance in pigs
Author(s):Liu, Yanhong
Director of Research:Pettigrew, James E.
Doctoral Committee Chair(s):Pettigrew, James E.
Doctoral Committee Member(s):Maddox, Carol W.; Johnson, Rodney W.; Bravo, David
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):cytokines
Escherichia. coli
immune responses
plant extracts
porcine alveolar macrophages
porcine reproductive and respiratory syndrome
Abstract:Plant extracts (PE) are bioactive substances, extracted from some foods or traditional herbs. It has been known that PE possess antioxidant, antibacterial, anti-inflammatory, and perhaps immunoregulatory effects. The 3 studies below demonstrate the anti-inflammatory effects of PE in vitro and the effect of PE on immune function and disease resistance of pigs in vivo. The first study evaluated the effects of 7 PE (anethol, capsicum oleoresin, carvacrol, cinnamaldehyde, eugenol, garlic, and turmeric oleoresin) on cell viability and cytokine secretion of porcine alveolar macrophages (PAM) with or without lipopolysaccharide (LPS) stimulation. Without LPS stimulation, anethol (35 to 52%) and capsicum oleoresin (39 to 59%) increased cell viability of PAM, whereas other PE reduced (P < 0.05) it. Anethol (12 to 34%), capsicum oleoresin (53 to 92%), or carvacrol (46 to 61%) enhanced (P < 0.05) the cell viability of LPS-treated PAM. Without LPS stimulation, anethol, capsicum oleoresin, cinnamaldehyde, or turmeric oleoresin stimulated TNF-α secretion from PAM, whereas all PE except eugenol enhanced IL-1β secretion from PAM. However, all PE suppressed (P < 0.05, 15 to 100%) TNF-α, and carvacrol, cinnamaldehyde, eugenol, or garlic decreased (P < 0.05, 31 to 95%) IL-1β secretion from LPS-induced PAM. This study indicates all PE may have potent anti-inflammatory effects to varying degrees. Based on the in vitro study, three PE (capsicum oleoresin (CAP), garlic (GAR), and turmeric oleoresin (TUR)) showing diverse effects in vitro were selected to investigate their effects in vivo with two different disease models, Escherichia coli (E. coli) and porcine reproductive and respiratory syndrome (PRRS). The second study evaluated the effects of 3 PE on diarrhea, immune response, intestina morphology, and growth performance of weaned pigs experimentally infected with a pathogenic F-18 E. coli. The E. coli infection increased (P < 0.05) white blood cells (WBC), tumor necrosis factor (TNF)-α, and hapotoglobin (Hp), and reduced overall ADG, G:F, and villi height (VH) of the small intestine as expected. In the challenged group, the supplementation of 10 mg of CAP, GAR, or TUR/kg diet reduced average diarrhea score from d 0 to 2 and d 6 to 11 and overall frequency of diarrhea, decreased (P < 0.05) TNF-α and Hp on d 5 and WBC and NEU on d 11, and increased (P < 0.05) ileal VH on d 5, and tended (P = 0.10) to increase jejunum VH and villi height:crypt depth compared with the control diet (CON). In the sham group, the PE treatments reduced (P < 0.05) average DS from d 3 to 5, overall frequency of diarrhea, and Hp on d 5, compared with the CON. In addition, the 3 PE tested here showed different influences on the inflammatory mediators. In conclusion, the 3 PE tested reduced diarrhea, increased the VH of the small intestine, and affected total WBC, the populations of immune cells, and inflammatory mediators in E. coli-infected piglets, which may be beneficial to pig health. The third study was conducted to determine the effects of these 3 PE on growth efficiency and immune responses of pigs experimentally infected with PRRS virus (PRRSV). Infection of PRRSV reduced pig performance (P < 0.01), but increased rectal temperature (RT), viral load (VL), and PRRSV specific antibody titer (AT), and serum inflammatory mediators (P < 0.05). In addition, the PRRSV infection reduced (P < 0.01) leukocytes on d 7, but increased (P < 0.01) leukocytes on d 14. In the PRRSV challenged group, the PE treatments increased (P < 0.05) growth efficiency, IL-10, and Hp, but reduced (P < 0.05) viral load, TNF-α, C-reactive protein, and RT on d 4 as compared to the CON. In the unchallenged group, all piglets were PRRSV negative during the overall period PI. The CAP increased (P < 0.05) ADFI from d 0 to 7 and overall period PI, and final weight of piglets compared with the CON. Similar to the second study with E. coli infection, the 3 PE tested showed diverse effects on growth efficiency and inflammatory mediators of pigs infected with PRRSV, and TUR appeared to strengthen the immune responses and efficiency of pigs infected with PRRSV. In summary, PE are potent s in both in vitro and in vivo systems. Dietary supplementation of different PE for pigs may bring different influences to pigs infected with a bacterial or viral model. In the E. coli infection model, PE may bring the benefits by preventing over-stimulation of the immune system, while in the PRRSV infection model, PE may exhibit the benefits by boosting the host’s disease resistance in the early stage of disease and maintaining it in the later stage.
Issue Date:2012-02-01
URI:http://hdl.handle.net/2142/29551
Rights Information:Copyright 2011 Yanhong Liu
Date Available in IDEALS:2014-02-01
Date Deposited:2011-12


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