185 Maternal live yeast supplementation protects newly weaned piglets against lipopolysaccharide challenge by regulating immune-associated milk proteins

Abstract Sow milk serves as a crucial source of nutritional, immunological, and growth-promoting components for the piglets. Our previous studies established that maternal live yeast (LY) supplementation altered the expression of antioxidant and immune-regulatory genes in the intestinal mucosa of suckling piglets. The current study aimed to investigate the effects of maternal LY supplementation during late gestation and lactation on milk proteomic profile in dams and health of offspring under lipopolysaccharide (LPS) challenge. On d 77 of gestation, 40 sows were allocated to 2 dietary treatments: without (CON) or with LY supplementation at 0.05% of diet during gestation and 0.1% during lactation. Milk samples were collected on d 0, 10, and 18 post-partum (n = 6), respectively. Within 24 h postweaning, piglets from the CON and LY groups were intraperitoneally injected with sterile saline or LPS [25 μg/kg body weight (BW)] and divided into four groups (n = 8): 1) saline + CON (CS), 2) saline + LY (YS), 3) LPS + CON (CLPS), and 4) LPS + LY (YLPS). Data were analyzed in a 2 × 2 factorial arrangement with main effects of maternal diet and immunological challenge. Rectal temperature was measured hourly for 4 h post-injection after which piglets were euthanized. Results showed that LPS increased concentrations of serum tumor necrosis factor (TNF) -α and interlekin (IL) -10 (P < 0.05) and tended to increase IL-8 in the ileal mucosa of piglets (P < 0.10). At 3 h post-injection, YLPS piglets tended to have a lower rectal temperature than CLPS piglets (P < 0.10). YLPS piglets also had decreased protein levels of TNF-α in the ileal mucosa (P < 0.05), with a tendency for greater protein abundance of E-cadherin but decreased mRNA abundance of catalase (P < 0.10) in the jejunal mucosa at 4 h post-injection (P < 0.05). In addition, YLPS piglets had less mRNA abundance of TLR2 and TLR4 in the liver than CLPS piglets (P < 0.05). With shotgun proteomics analysis, we found that milk of LY sows had more abundant proteins associated with immunity, including immunoglobulin and complement protein (Ig-like and C1q domain-containing proteins) on d 0 and d 10. Insulin-like growth factor binding protein (IGFBP) 5 was also more abundant in the d 0 milk of LY sows, whereas prostaglandin synthase was greater in d 10 and d 18 milk of CON sows. Additionally, pathway analysis showed that proteins identified in the milk of CON sows have roles in neutrophil degranulation and IL-12 signaling and production, whereas pathways associated with regulation of complement system, IGF and DHCR24 signaling, were enriched in the milk of LY sows. These results suggest that maternal LY supplementation could protect newly weaned piglets from bacteria endotoxin effect by suppressing inflammatory response, improving expression of tight junction proteins in offspring, and altering immune-associated proteins in sow milk.