N-glycosylation of immunoglobulin G (IgG) has been reported to change in human aging and in some age-related diseases. To further understand the molecular processes that determine these alterations, a detailed examination of individual IgG N-glycans with aging remains required. Mouse is the most commonly used model animal in studies of aging and age-related diseases, and mice have the advantage of relatively controllable genetic and environment variations compared to human. In this study, we systemically investigated the changes in serum IgG N-glycome in C57BL/6 mice during aging at 12 time points (6–80 weeks) via ultraperformance liquid chromatography with fluorescence detection. The study demonstrated several important findings. First, four chromatographic IgG N-glycan peaks were identified for the first time, including a high-mannose glycan, a monoantennary glycan, and two afucosylated glycans. Second, most of the IgG glycan levels changed significantly and presented pronounced gender-related differences from 6 to 12 weeks. Interestingly, all the IgG glycan levels tended to be similar between male and female mice at 12 weeks. Third, the level of fucosylated diantennary glycans containing one N-glycolylneuraminic acid (Neu5Gc)-linked N-acetyllactosamine (LacNAc) decreased gradually and showed a significant negative correlation with age from 24 to 80 weeks (r = −0.716, p < 0.0001), which was not sex-specific.

Significance

More comprehensive profile of murine IgG N-glycans by ultraperformance liquid chromatography with fluorescence detection was shown in this study with four newly identified chromatographic murine IgG N-glycan peaks. The majority of IgG N-glycans showed substantial stage-specific changes and sex-related differences during mouse aging, indicating a strict regulatory mechanism of glycan synthesis. The level of fucosylated diantennary glycans containing one Neu5Gc-linked LacNAc was significantly negatively correlated with age from 24 to 80 weeks, suggesting its great potential as an aging biomarker. The detailed characteristics of IgG N-glycosylation with aging in C57BL/6 mice demonstrated in the present study could provide essential reference data for studying the function and mechanism of IgG glycosylation in age-related researches based on C57BL/6 mouse models.

中文翻译：

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小鼠衰老过程中IgG N-糖基的分析：岩藻糖基化的双触角聚糖含有一种与Neu5Gc连接的LacNAc的糖基化与年龄有关。

据报道，免疫球蛋白G（IgG）的N-糖基化会在人类衰老和某些与年龄有关的疾病中发生变化。为了进一步了解决定这些改变的分子过程，仍然需要对具有衰老作用的各个IgG N-聚糖进行详细检查。在衰老和与年龄相关的疾病研究中，小鼠是最常用的模型动物，与人类相比，小鼠具有相对可控的遗传和环境变异优势。在这项研究中，我们通过具有荧光检测功能的超高效液相色谱系统研究了C57BL / 6小鼠衰老过程中12个时间点（6-80周）血清IgG N-糖基的变化。该研究表明了几个重要发现。首先，首次鉴定了四个色谱IgG N-聚糖峰，包括高甘露糖聚糖，一个单触角聚糖和两个岩藻糖基化聚糖。其次，大多数IgG聚糖水平在6到12周内发生了显着变化，并呈现出明显的性别相关差异。有趣的是，在12周时，雄性和雌性小鼠之间的所有IgG聚糖水平都趋于相似。第三，岩藻糖基化双触角聚糖的水平，其中含有一种N-羟甲基神经氨酸（Neu5Gc）N-乙酰基乳糖胺（LacNAc）逐渐降低，并且与年龄从24周到80周呈显着负相关（r  = -0.716，p  <0.0001），这与性别无关。

意义

通过具有荧光检测的超高效液相色谱，通过四个新鉴定的色谱鼠IgG N-聚糖峰显示了鼠IgG N-聚糖的更全面的概况。大多数IgG N-聚糖在小鼠衰老过程中表现出明显的阶段特异性变化和性别相关差异，表明聚糖合成具有严格的调节机制。含有一种Neu5Gc连接的LacNAc的岩藻糖基化双触角聚糖的水平与24至80周龄显着负相关，表明其作为衰老生物标记物的潜力很大。