The effects of in utero heat stress (IUHS) range from decreased growth performance to altered behavior, but the long-term impact of IUHS on postnatal innate immune function in pigs is unknown. Therefore, the study objective was to determine the effects of early gestation IUHS on the immune, metabolic, and stress response of pigs subjected to an 8 hr lipopolysaccharide (LPS) challenge during postnatal life. Twenty-four pregnant gilts were exposed to thermoneutral (TN; n = 12; 17.5 ± 2.1 °C) or heat stress (HS; n = 12; cyclic 26 to 36 °C) conditions from days 6 to 59 of gestation, and then TN conditions (20.9 ± 2.3 °C) from day 60 of gestation to farrowing. At 12 wk of age, 16 IUHS and 16 in utero thermoneutral (IUTN) pigs were selected, balanced by sex and given an intravenous injection of LPS (2 µg/kg BW mixed with sterile saline [SAL] and injected at 2 µL/kg BW) or SAL (2 µL/kg BW). Body temperature was monitored every 30 min, and blood was obtained at 0, 1, 2, 3, 4, 6, and 8 hr following the LPS challenge. Blood samples were analyzed for glucose, insulin, non-esterified fatty acids (NEFA), cortisol, and cytokine concentrations. In addition, white blood cell counts were determined at 0 and 4 hr. Hour 0 data were used as covariates. Body temperature was increased (P < 0.01) in LPS (40.88 ± 0.08 °C) vs. SAL (39.83 ± 0.08 °C) pigs. Eosinophils tended to be decreased overall (P = 0.09; 43.9%) in IUHS vs. IUTN pigs. Glucose concentrations were reduced overall (P = 0.05; 5.9%) in IUHS vs. IUTN pigs. The NEFA concentrations tended to be greater (P = 0.07; 143.4%) in IUHS-LPS pigs compared with all other treatments, and IUTN-LPS pigs tended to have greater (127.4%) circulating NEFA concentrations compared with IUTN-SAL and IUHS-SAL pigs. Cortisol was increased (P = 0.04) in IUHS-LPS compared with IUTN-LPS pigs at 3 hr (21.5%) and 4 hr (64.3%). At 1 hr, tumor necrosis factor α was increased (P = 0.01; 115.1%) in IUHS-LPS compared with IUTN-LPS pigs. Overall, interleukin-1β (IL-1β) and interleukin-6 (IL-6) were greater (P < 0.04; 281.3% and 297.8%, respectively) in IUHS-LPS pigs compared with all other treatments, and IUTN-LPS pigs had increased IL-1β and IL-6 concentrations compared with IUTN-SAL and IUHS-SAL pigs. In summary, IUHS altered the postnatal cytokine, metabolic, and physiological stress response of pigs during postnatal life, which may have negative implications toward the innate immune response of IUHS pigs to pathogens.

中文翻译：

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子宫内热应激改变猪的出生后先天免疫反应

宫内热应激 ( IUHS ) 的影响范围从生长性能下降到行为改变，但 IUHS 对猪出生后先天免疫功能的长期影响尚不清楚。因此，本研究的目的是确定妊娠早期 IUHS 对出生后接受 8 小时脂多糖 ( LPS ) 攻击的猪的免疫、代谢和应激反应的影响。24 头怀孕的小母猪暴露于热中性 ( TN ; n = 12; 17.5 ± 2.1 °C) 或热应激 ( HS ; n= 12; 从妊娠第 6 天到第 59 天循环 26 至 36 °C) 条件，然后从妊娠第 60 天到分娩采用 TN 条件 (20.9 ± 2.3 °C)。在 12 周龄时，选择 16 头 IUHS 和 16 头宫内热中性 ( IUTN ) 猪，按性别平衡并静脉注射 LPS（2 µg/kg BW 与无菌盐水 [ SAL ]混合，注射量为 2 µL/kg BW) 或 SAL (2 µL/kg BW)。每 30 分钟监测一次体温，并在 LPS 攻击后 0、1、2、3、4、6 和 8 小时采集血液。分析血液样本的葡萄糖、胰岛素、非酯化脂肪酸 ( NEFA )、皮质醇和细胞因子浓度。此外，在 0 和 4 小时测定白细胞计数。小时 0 数据用作协变量。体温升高（P < 0.01) 在 LPS (40.88 ± 0.08 °C) 与 SAL (39.83 ± 0.08 °C) 猪中。IUHS 与 IUTN 猪的嗜酸性粒细胞总体上趋于减少（P = 0.09；43.9%）。IUHS 与 IUTN 猪的葡萄糖浓度总体上降低（P = 0.05；5.9%）。与所有其他处理相比，IUHS-LPS 猪的 NEFA 浓度往往更高（P = 0.07；143.4%），而 IUTN-LPS 猪的循环 NEFA 浓度往往高于 IUTN-SAL 和 IUHS- SAL猪。与 IUTN-LPS 猪相比，IUHS-LPS 的皮质醇在 3 小时（21.5%）和 4 小时（64.3%）时增加（P = 0.04）。在 1 小时时，肿瘤坏死因子 α 增加（P= 0.01; 115.1%) 在 IUHS-LPS 中与 IUTN-LPS 猪相比。总体而言，IUHS-LPS 猪与所有其他处理和 IUTN-LPS 猪相比，IL-1β ( IL-1β ) 和 IL-6 ( IL-6 ) 更高（P < 0.04；分别为 281.3% 和 297.8%）与 IUTN-SAL 和 IUHS-SAL 猪相比，IL-1β 和 IL-6 浓度增加。总之，IUHS 改变了猪在出生后的出生后细胞因子、代谢和生理应激反应，这可能对 IUHS 猪对病原体的先天免疫反应产生负面影响。