Giant pandas (Ailuropoda melanoleuca) possess highly specialized reproductive characteristics, but the maternal immune changes during reproduction are largely unclear. Here, 20 blood transcriptomes were used to determine immune changes at four key phases of giant panda reproduction, and a total of 4640 differential expression genes were identified. During estrus, six immune-related genes (TLR4, IL1B, SYK, SPI1, CD80, and ITK) were identified as hub genes. The up-regulation of the TLR family genes (TLR4, TLR5, TLR6, and TLR8) and inflammatory response related genes (IL1B) may reflect innate immune enhancement and local tissue remodeling events, while the up-regulation of SYK and SPI1, and the down-regulation of CD80 and ITK suggested that the enhanced humoral immunity and inhibited cellular immunity of female giant pandas during estrus. During early pregnancy, antigen presentation related genes and proinflammatory cytokine (IL1B) were down-regulated. This may indicate that partial immune functions were suppressed in early pregnancy to achieve immune tolerance, including reducing inflammatory to protect embryos. By the late pregnancy, the antiviral related genes were up-regulated to strengthen defenses against external pathogen infection. KLRK1, which acts as a primary activation receptor for NK cells, was down regulated in estrus and pregnancy, suggesting that the activities of NK cells were inhibited, and KLRK1 may play a key role in the regulation the activities of pbNK cells during reproduction of giant pandas. Our results showed that there was no significant immune change in lactating females (post-natal 2 months) compared to anestrus females. This is the first time to observe the immune changes of giant panda during the breeding period and our data is expected to provide valuable resources for further studies on reproductive immunology of giant pandas.

中文翻译：

---

转录组分析提供了对大熊猫繁殖几个关键阶段母体免疫变化的见解。

大熊猫（Ailuropoda melanoleuca）具有高度特化的繁殖特征，但繁殖过程中母体的免疫变化尚不清楚。在这里，20个血液转录组被用于确定大熊猫繁殖四个关键阶段的免疫变化，共鉴定出4640个差异表达基因。在发情期间，六个免疫相关基因（TLR4、IL1B、SYK、SPI1、CD80 和 ITK）被确定为枢纽基因。TLR 家族基因（TLR4、TLR5、TLR6 和 TLR8）和炎症反应相关基因（IL1B）的上调可能反映了先天免疫增强和局部组织重塑事件，而 SYK 和 SPI1 的上调，以及CD80和ITK的下调提示雌性大熊猫在发情期体液免疫增强，细胞免疫受到抑制。在妊娠早期，抗原呈递相关基因和促炎细胞因子（IL1B）被下调。这可能表明部分免疫功能在妊娠早期被抑制以实现免疫耐受，包括减少炎症以保护胚胎。到妊娠晚期，抗病毒相关基因被上调，以加强对外部病原体感染的防御。KLRK1 作为 NK 细胞的主要激活受体，在发情期和妊娠期下调，提示 NK 细胞的活性受到抑制，KLRK1 可能在巨熊猫。我们的结果表明，与无情期雌性相比，哺乳期雌性（产后 2 个月）没有显着的免疫变化。