34 Assessing the Ability to Immunomodulate the Innate Immune System and Oxidative Status of Weaned Pigs Through a Prenatal Lipopolysaccharide Challenge

Abstract

Abstract Gastrointestinal immunity and antioxidant defenses may be bolstered in young animals through prenatal immune system stimulation (PIS), but this is largely uninvestigated in swine. The objective of this experiment was to determine if a low dose of lipopolysaccharide (LPS) administered to late-gestating sows would alter the immune response and oxidative status of subsequent offspring. On d 78 ± 1.8 of gestation, 14 Camborough sows (Parity = 2.6±1.4) of the same farrowing group were blocked by body weight and randomly assigned to one of two treatments: intramuscular injection of saline (CON) or LPS from E. coli O111:B4 (2.5 µg/kg of BW). Sow rectal temperatures (RT) and sickness behavior scores (SBS) were recorded every 0.5 h from -0.5 h to 8 h and every 8 h from 8 to 48 h post-treatment. A subset of 34 weaned barrows (n = 17 CON, LPS; weaning age 21 ± 1.3 d) from the experimental sow group were transported on d -7 to an environmentally controlled facility where they were individually housed with ad libitum access to water and feed. On d -1, pigs were anesthetized for placement of a subcutaneous temperature logger and a jugular catheter. On d 0, all pigs were challenged intravenously with the same LPS strain (10 µg/kg of BW) previously administered to sows. Body temperature was measured at 5-min intervals from the time of logger placement. Blood samples were collected at -2, 0, 1, 2, 4, 6, 8, 12, and 24 h relative to LPS administration at 0 h. After the 24 h blood collection, pigs were necropsied for ileal and jejunal tissue. Plasma samples, jejunal and ileal tissues were analyzed for total antioxidant capacity (TAC) and malondialdehyde (MDA). Data were analyzed as a linear mixed model using PROC MIXED (SAS 9.4) with treatment and time as fixed effects. A dependent covariance structure was used for repeated measurements. Sows administered LPS had elevated RT from 2 to 16-h post-challenge with return to baseline by h 24, indicating mild immune stimulation (treatment × time; P < 0.01). Similarly, sows exposed to LPS had increased SBS from 2 to 3.5 h post-challenge (treatment × time; P < 0.01). Pigs exposed to PIS had greater body temperature than CON at 1 and 2 h post-LPS (treatment × time; P < 0.01). An increase in plasma TAC at 2 and 4 h post-LPS was observed in pigs exposed to PIS relative to CON (treatment × time; P < 0.01). Irrespective of treatment, LPS increased plasma MDA from 2 to 24 h post-challenge (time; P < 0.01). There was no effect of PIS on ileal or jejunal tissue TAC (P ≥ 0.40), but weaned pigs exposed to PIS had decreased jejunal MDA (P < 0.05). Collectively, it appears PIS may alter the innate immune response and oxidative status of the weaned pig during LPS challenge.