Saleh Khaled M M, Al-Zghoul Mohammad B
Department of Applied Biological Sciences, Faculty of Science and Art, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan.
Department of Basic Medical Veterinary Sciences, Faculty of Veterinary Medicine, Jordan University of Science and Technology, P.O. Box 3030, Irbid 22110, Jordan.
Animals (Basel). 2019 Jul 29;9(8):499. doi: 10.3390/ani9080499.
Heat stress significantly impacts the immunity and cytokine expression of chickens. However, the effects of embryonic thermal manipulation (TM) on cytokine expression in broiler chickens (broilers) is unclear. The objective of the current study was to evaluate the effects of TM on the splenic mRNA expression dynamics of certain cytokines-namely, IFN-α, IFN-β, IFN-γ, IL-4, IL-8, IL-15, IL-16, IL-17, and IL-18-in broilers during subsequent exposure to acute heat stress (AHS). TM was performed by elevating the incubation temperature to 39 °C at 65% relative humidity (RH) for 18 h daily during embryonic days (ED) 10-18. On post-hatch day 28, AHS was carried out for 7 h at 40 °C. At 0 h and after 1, 3, 5, and 7 h of AHS, splenic tissues were collected from all study groups to evaluate mRNA expression by relative-quantitative real-time (RT)-PCR. Plasma was collected to measure IL-4, IL-8, and IFN-γ levels. At 0 h, TM significantly reduced the basal mRNA level of IFN-β and the plasma level of IFN-γ and IL-8. Moreover, AHS significantly decreased IFN-β in control chicks, decreased IL-4 in both TM and control chicks, and increased IFN-γ and IL-16 in TM chicks. IFN-α, IL-8, IL-15, IL-17, and IL-18 expression all significantly increased during AHS in both TM and control chicks, but expression dynamics were improved in TM chicks for all cytokines (except IL-17). AHS resulted in increased plasma IFN-γ levels in TM chicks only, and increased IL-8 levels at 3 and 5 h of AHS in TM chicks, but at 7 h in control chicks. Lastly, 3 h of AHS increased IL-4 plasma levels in control chicks. The results of this study may indicate that TM has a long-term effect on cytokine expression dynamics of broilers, especially during AHS. Therefore, TM may improve heat tolerance acquisition by increasing the expression of signaling proteins important to tissue stability and to repair mechanisms that are employed during and/or after heat stress recovery.
热应激对鸡的免疫力和细胞因子表达有显著影响。然而，胚胎期热调控（TM）对肉鸡细胞因子表达的影响尚不清楚。本研究的目的是评估TM对肉鸡在随后暴露于急性热应激（AHS）期间某些细胞因子（即IFN-α、IFN-β、IFN-γ、IL-4、IL-8、IL-15、IL-16、IL-17和IL-18）脾脏mRNA表达动态的影响。在胚胎期（ED）10至18天，通过将孵化温度提高到39°C、相对湿度（RH）65%，每天处理18小时来进行TM。在孵化后第28天，在40°C进行7小时的AHS。在AHS的0小时以及1、3、5和7小时后，从所有研究组收集脾脏组织，通过相对定量实时（RT）-PCR评估mRNA表达。收集血浆以测量IL-4、IL-8和IFN-γ水平。在0小时，TM显著降低了IFN-β的基础mRNA水平以及IFN-γ和IL-8的血浆水平。此外，AHS显著降低了对照雏鸡中IFN-β的水平，降低了TM雏鸡和对照雏鸡中IL-4的水平，并增加了TM雏鸡中IFN-γ和IL-16的水平。在TM雏鸡和对照雏鸡的AHS期间，IFN-α、IL-8、IL-15、IL-17和IL-18的表达均显著增加，但所有细胞因子（IL-17除外）在TM雏鸡中的表达动态有所改善。AHS仅导致TM雏鸡血浆IFN-γ水平升高，TM雏鸡在AHS的3和5小时IL-8水平升高，而对照雏鸡在7小时升高。最后，3小时的AHS增加了对照雏鸡的IL-4血浆水平。本研究结果可能表明，TM对肉鸡的细胞因子表达动态有长期影响，尤其是在AHS期间。因此，TM可能通过增加对组织稳定性以及热应激恢复期间和/或之后所采用的修复机制重要的信号蛋白的表达来提高耐热性。
