Pro-inflammatory cytokines and reproductive hormone responses in bucks post-challenge with Mannheimia haemolytica A2 and its outer membrane protein

AbstractThe lipopolysaccharide (LPS) endotoxin and outer membrane protein (OMP) are among the virulence factors of Gram-negative bacteria responsible for inducing pathogenicity in the infected host. OMP and LPS occur on the outer membrane ofM. haemolytica A2, the primary aetiological agent of pneumonic mannheimiosis in small ruminants. While the LPS is known to mediate Gram-negative bacterial infection by activating downstream inflammatory pathways, the potential role of OMP during inflammatory responses remained unclear. Hence, this study determined the effect of the OMP ofM. haemolytica A2 on the serum concentration of pro-inflammatory cytokines and the male reproductive hormones (testosterone and Luteinizing Hormone). We randomly assigned twelve bucks to three groups (n = 4 bucks each): Group 1 was challenged with 2 mL PBS buffer (pH 7.0) intranasally; Group 2 received 2 mL of 1.2 X 109 CFU/mL wholeM. haemolytica A2 intranasally; and Group 3 received 2  mL of OMP extract obtained from 1.2 X 109 CFU/mLM. haemolytica A2 intramuscularly. Serum samples collected at pre-determined intervals were used for the quantitative determination of the pro-inflammatory cytokines (IL-1 β, IL-6, and TNFα) and reproductive hormones (testosterone and LH) using commercial sandwich enzyme-linked immunosorbent assay (ELISA). The serum concentration of IL1β was initially increased within the first-hour post-challenge in Groups 2 and 3, followed by a significant decrease in concentrati...
Source: Tropical Animal Health and Production - Category: Veterinary Research Source Type: research