Spleen proteome profile reveals immune responses induced by dietary spray-dried plasma against Salmonella Enteritidis infection in broiler chicks

Salmonella infection severely impacts poultry health, productivity, and food safety. Spray dried plasma (SDP) shows good efficacy as an alternative to in-feed antibiotics for broiler chickens. Our objective was to identify potential mechanisms of SDP benefits by analyzing effects on spleen proteome and in response to Salmonella Enteritidis challenge (SE). A 2 × 2 factor study of broilers (n = 240) were assigned to CON (control) or SDP (30g/kg) diet at 1 day of age, and gavaged with tryptic soy or 7.46 × 10⁸ CFU SE /mL, resulting in 4 groups CON (n=60), SDP (n=60), CON-SE (n=60) and SDP-SE (n=60). On d 2 and d 5 post-challenge, chicks (n=4/treatment) were euthanized, and spleen collected to isolate proteins, and measure using label-free liquid chromatography tandem mass spectrometry. Data were mapped to Gallus gallus Uniprot database, and differentially abundant proteins (DAP; P<0.05) identified using ANOVA. Across all samples, 4,300 proteins were identified, and SDP treatment resulted 116 DAP. Proteins (56) that decreased were associated with positive regulation of I-kappaß kinase/NF- kappaß signaling and positive regulation of apoptosis process. Proteins that increased (60) were associated with integral components of endoplasmic reticulum membrane and necroptosis pathway. Analysis of the interaction between SDP and SE challenge found 119 DAP. The proteins that increased (87) were associated with RNA binding, ATP binding, mRNA splicing, and protein phosphorylation. Proteomic signatures of spleen reveals that the actions of SDP in broiler chicks are anti-inflammatory and anti-apoptotic and predicted to inhibit pro-inflammatory response through the inhibition of NF-ĸB. However, in the presence of Salmonella infection, it promotes regulated inflammatory response.