The Anti-Inflammatory Effect of Cowpea Polyphenol in Bovine Blood

The objective of this study was to investigate the effect of crude cowpea polyphenol extract (CPE) on the expression of genes involved in the inflammatory response in bovine blood in vitro. Plant-derived polyphenols in animal feeds are being used as alternatives to antibiotics to treat and prevent invading microbes. These compounds have antioxidant and anti-inflammatory properties and are able to modulate immune and inflammation responses. Whole blood collected from lactating Holstein-Friesian cows (n=10) were incubated with 10 µg of CPE for 60 min at 37^oC, and 5% CO₂.Total RNA was extracted from whole blood after incubation, reverse transcribed to cDNA, and quantitative PCR (qPCR) was performed using the cow inflammatory cytokines and receptor array (Qiagen) with 84 genes. The qPCR data were analyzed using Livak’s method to calculate fold change in gene expression between CPE-treated and control. Normalization of data was performed with GAPDH as an internal control. Out of the 84 genes tested, 81 were expressed, 13 upregulated and 68 downregulated in response to CPE. Treatment with CPE downregulated the expression of proinflammatory cytokine TNFα [fold change (FC= treatment/control= -43.39), IL1α (FC= -6.19), ILβ (FC= -3.62), and IL8 (FC= -1.25). Expression of chemokines such as CXCL10, CXCL12 and CXCR2 was not altered by treatment with CPE. Interestingly, expression of IL10RA (FC=3.39), a receptor for IL10 a well-known anti-inflammatory cytokine was upregulated in blood incubated with CPE. Interleukin 15, a cytokine that regulates T and natural killer cell activation and proliferation was upregulated (FC=2.08) by CPE treatment. The study results demonstrate that polyphenols derived from cowpea have an anti-inflammatory effect in cow blood and target genes modulated by CPE have been identified for further characterization.