背景:IgA肾病(IgAN)是一种肾脏疾病,其特征是与半乳糖缺陷型IgA1(Gd-IgA1)结合的IgG的循环免疫复合物在肾小球系膜肾小球中沉积。然而,关于IgA结合水平与IgAN中IgG的各种唾液酸化特征的关系,已经进行了有限的研究。
方法:从IgAN患者中分离唾液酸化IgG(SA-IgG)和去唾液酸化IgG(DSA-IgG)。使用两种定制的商业ELISA试剂盒检测IgG-IgA免疫复合物(IgG-IgA-IC)。此外,用神经氨酸酶酶消化IgG以产生DSA-IgG。随后,使用ELISA试剂盒测定完整IgG和神经氨酸酶消化的DSA-IgG与Gd-IgA1的结合能力.
结果:我们的研究表明,在IgAN患者中,SA-IgG水平与Gd-IgA1呈负相关(R=-0.16,p=0.03)。当使用Gd-IgA1测定试剂盒时,与DSA-IgG样品(0.78±0.12)相比,SA-IgG样品中IgG-IgA复合物的光密度(OD)水平显著更低(0.58±0.09)。使用IgG检测试剂盒证实了这些结果,结果表明,SA-IgG组的IgA指数(0.31±0.12)明显低于DSA-IgG组(0.57±0.19)。此外,我们研究了不同唾液酸水平的IgG与Gd-IgA1的结合能力。结果显示,IgG的神经氨酸酶消化增加了其与Gd-IgA1结合的倾向。此外,我们检查了完整IgG和DSA-IgG在不同混合比例下与Gd-IgA1的结合能力(IgG1.5µg和Gd-IgA11.5µg,IgG1.5µg和Gd-IgA13µg,IgG3µg和Gd-IgA11.5µg)。有趣的是,在测试的所有混合比率下,与完整IgG相比,DSA-IgG显示出与Gd-IgA1的显著更高的结合能力。
结论:我们本研究的初步发现表明,纯化的唾液酸化IgG中IgA的结合水平低于去唾液酸化IgG。
BACKGROUND: IgA nephropathy (IgAN) is a kidney disorder characterized by the deposition of circulating immune complexes of IgG bound to galactose-deficient IgA1 (Gd-IgA1) in the mesangial glomeruli. However, limited research has been conducted on the levels of IgA binding in relation to the various sialylation profiles of IgG in IgAN.
METHODS: Sialylated IgG (SA-IgG) and desialylated IgG (DSA-IgG) were isolated from IgAN patients. The IgG-IgA immune complex (IgG-IgA-IC) was detected using two customized commercial ELISA kits. Additionally, IgG was enzymatically digested with neuraminidase to produce DSA-IgG. Subsequently, the binding capacities of both intact IgG and the neuraminidase-digested DSA-IgG with Gd-IgA1 were determined using ELISA kits.
RESULTS: Our research revealed that SA-IgG levels were negatively correlated with Gd-IgA1 (R = -0.16, p = 0.03) in IgAN patients. The optical density (OD) levels of IgG-IgA complexes in SA-IgG samples were significantly lower (0.58 ± 0.09) compared to those in DSA-IgG samples (0.78 ± 0.12) when using the Gd-IgA1 assay kit. These results were confirmed using an IgG assay kit, which showed that the SA-IgG groups had significantly lower IgA indices (0.31 ± 0.12) compared to the DSA-IgG groups (0.57 ± 0.19). Furthermore, we investigated the binding capacity of IgG with different sialic acid levels to Gd-IgA1. The results revealed that neuraminidase digestion of IgG increased its propensity to bind to Gd-IgA1. Additionally, we examined the binding capacity of both intact IgG and DSA-IgG to Gd-IgA1 at different mix ratios (IgG 1.5 µg and Gd-IgA1 1.5 µg, IgG 1.5 µg and Gd-IgA1 3 µg, IgG 3 µg and Gd-IgA1 1.5 µg). Interestingly, DSA-IgG demonstrated significantly higher binding capacity to Gd-IgA1 compared to intact IgG at all mix ratios tested.
CONCLUSIONS: The preliminary findings from our present study indicate that the binding level of IgA in purified sialylated IgG is lower than that in desialylated IgG.