Immunomodulatory activities of polyphenol extract from Cowpea (Vigna unguiculata) on bovine polymorphonuclear neutrophils

Abstract Text:

The response of the bovine neutrophils to bacterial endotoxin and its significance in the inflammatory response has been studied widely.  Studies have also shown that a Cowpea diet is protein-rich and contains phenolic compounds with antioxidant properties beneficial for animal health and wellbeing. In this study, the effect of a polyphenol extract (CPE) from cowpea (Vigna unguiculata) on modulation of the response to endotoxin from gram negative bacteria was evaluated. Secretion of mediators of inflammation, such as cytokines, and prostaglandin E2 (PGE2), and expression of innate immune response genes by LPS stimulated bovine polymorphonuclear neutrophils (PMNs) were measured. Neutrophils were isolated from whole blood collected from Holstein-Friesian cows (n=10) in mid-lactation. Lipopolysaccharide-stimulated PMNs were treated with 10 ug/ml of CPE. The secretion of cytokines (TNF-α, IFNγ, GM-CSF, G-CSF, IL-1A, IL-8, IP10, and RANTES), and prostaglandin E2 (PGE2) were measured using commercial ELISAs. Real-time qRT-PCR was performed using an innate and adaptive immune response array with 84 test genes. Cowpea polyphenolic extracts decreased PGE2 levels (8.2 ± 2.5 pg/ml) in LPS-stimulated PMNs, relative to control LPS-only treated PMNs (48.7 ± 4.1 pg/ml). Treatment with CPE resulted in decreased concentrations of six of the tested cytokines, except GM-CSF and IP10. Real-time qRT-PCR analysis of LPS-exposed PMNs revealed down-regulation of proinflammatory cytokines (TNF-α, IL-1A, IL-1B, IL-8) and  transcription factor NF-kB, and up-regulation of anti-inflammatory cytokine IL13(8.4 folds) by the cowpea phenolic extract. Thus cowpea polyphenolic extract may exert their anti-inflammatory activities and modulate innate immune response through modulation of the neutrophil under pathogen- induced conditions in cows. Therefore, integrating and utilizing cowpea into animal production system may enhance nutrition and improved health and needs further study.

Keywords: Bovine, Cowpea, Cytokines,  Phenolic compounds, Polymorphonuclear neutrophils, Prostaglandin E2