Veuskens Bert R J, Brouwer Mieke C, van Mierlo Gerard, Geissler Judy, van Leeuwen Karin, Derlagen Maaike, Keijzer Nadia C H, Hoogenboezem Mark, Kuijpers Taco W, Pouw Richard B
Sanquin Research and Landsteiner Laboratory of the Amsterdam University Medical Centers, University of Amsterdam, Plesmanlaan 125, 1066 CX, Amsterdam, The Netherlands.
Amsterdam Institute for Immunology and Infectious Diseases, Inflammatory Diseases, Amsterdam, The Netherlands.
Sci Rep. 2025 Mar 28;15(1):10669. doi: 10.1038/s41598-025-94064-4.
Factor H-related (FHR) protein 1 and 2 form dimers resulting in FHR-1 and -2 homodimers, and FHR-1/2 heterodimers. Dimerization is hypothesized to further increase their antagonistic function with complement regulator factor H (FH). So far, only FHR-1 homodimers and FHR-1/2 heterodimers could be quantified in a direct way. With the reported genetic associations between CFHR2 and complement-related diseases such as age related macular degeneration and C3-glomerulopathy, direct assessment of FHR-2/2 levels determining the dimer distribution of FHR-1 and -2 is needed to further elucidate their role within complement regulation. Therefore, novel in-house generated FHR-2 antibodies were used to develop a specific ELISA to enable direct quantification of FHR-2 homodimers. Allowing for the first time the accurate measurement of all FHR-1 and -2 containing dimers in a large cohort of healthy donors. By using native FHR-1 and -2 or deficient plasma, we determined the stability, kinetics and distribution of FHR-1 and -2 dimers. Additionally, we show how genetic variants influence dimer levels. Our results confirm a rapid, dynamic, dimer formation in plasma and show FHR-1/2 dimerization rearches a distribution equilibrium that is limited by the relative low levels of FHR-2 in relation to its dimerization partner FHR-1.
H因子相关（FHR）蛋白1和2形成二聚体，产生FHR-1和-2同型二聚体以及FHR-1/2异型二聚体。据推测，二聚化会进一步增强它们与补体调节因子H（FH）的拮抗功能。到目前为止，只有FHR-1同型二聚体和FHR-1/2异型二聚体能够以直接的方式进行定量。鉴于已报道的CFHR2与年龄相关性黄斑变性和C3肾小球病等补体相关疾病之间的遗传关联，需要直接评估决定FHR-1和-2二聚体分布的FHR-2/2水平，以进一步阐明它们在补体调节中的作用。因此，使用新产生的内部FHR-2抗体开发了一种特异性酶联免疫吸附测定（ELISA），以直接定量FHR-2同型二聚体。这首次使得能够在一大群健康供体中准确测量所有含FHR-1和-2的二聚体。通过使用天然FHR-1和-2或缺陷血浆，我们确定了FHR-1和-2二聚体的稳定性、动力学和分布。此外，我们展示了基因变异如何影响二聚体水平。我们的结果证实血浆中存在快速、动态的二聚体形成，并表明FHR-1/2二聚化达到一种分布平衡，该平衡受FHR-2相对于其二聚化伙伴FHR-1的相对低水平限制。
