Bridging the Species Divide: Transgenic Mice Humanized for Type-I Interferon Response

We have generated transgenic mice that harbor humanized type I interferon receptors (IFNARs) enabling the study of type I human interferons (Hu-IFN-Is) in mice. These “HyBNAR” (Hybrid IFNAR) mice encode transgenic variants of IFNAR1 and IFNAR2 with the human extracellular domains being fused to transmembrane and cytoplasmic segments of mouse sequence. B16F1 mouse melanoma cells harboring the HyBNAR construct specifically bound Hu-IFN-Is and were rendered sensitive to Hu-IFN-I stimulated anti-proliferation, STAT1 activation and activation of a prototypical IFN-I response gene (MX2). HyBNAR mice were crossed with a transgenic strain expressing the luciferase reporter gene under the control of the IFN-responsive MX2 promoter (MX2-Luciferase). Both the HyBNAR and HyBNAR/MX2-Luciferase mice were responsive to all Hu-IFN-Is tested, inclusive of IFNα2A, IFNβ, and a human superagonist termed YNSα8. The mice displayed dose-dependent pharmacodynamic responses to Hu-IFN-I injection, as assessed by measuring the expression of IFN-responsive genes. Our studies also demonstrated a weak activation of endogenous mouse interferon response, especially after high dose administration of Hu-IFNs. In sharp contrast to data published for humans, our pharmacodynamic readouts demonstrate a very short-lived IFN-I response in mice, which is not enhanced by sub-cutaneous (SC) injections in comparison to other administration routes. With algometric differences between humans and mice taken into account, the HyBNAR mice provides a convenient non-primate pre-clinical model to advance the study of human IFN-Is.

本研究构建了携带人源化I型干扰素受体（IFNARs）的转基因小鼠，可实现在小鼠体内对人源I型干扰素（Hu-IFN-Is）的相关研究。这批“HyBNAR（杂交干扰素受体，Hybrid IFNAR）”小鼠编码IFNAR1与IFNAR2的转基因变体：其人源胞外结构域与小鼠序列的跨膜段及胞质段相融合。
携带HyBNAR构建体的B16F1小鼠黑色素瘤细胞可特异性结合Hu-IFN-Is，并对Hu-IFN-I介导的抗增殖、STAT1激活及典型I型干扰素应答基因（MX2）的激活呈现敏感性。
将HyBNAR小鼠与在IFN应答性MX2启动子调控下表达荧光素酶（luciferase）报告基因的转基因品系（MX2-荧光素酶）进行杂交。结果显示，HyBNAR小鼠及HyBNAR/MX2-荧光素酶双转基因小鼠对所有受试Hu-IFN-Is均产生应答，涵盖IFNα2A、IFNβ以及被命名为YNSα8的人源超级激动剂。
通过检测干扰素应答基因的表达水平评估发现，这些小鼠对Hu-IFN-I注射呈现剂量依赖性的药效学应答。本研究同时观察到内源性小鼠干扰素应答存在微弱激活，尤其在高剂量Hu-IFNs给药后更为显著。
与已发表的人类研究数据形成鲜明对比的是，本研究的药效学检测结果显示，小鼠体内的I型干扰素应答存续时间极短，且与其他给药途径相比，皮下注射（SC）并未增强该应答。
考虑到人类与小鼠之间的种间剂量换算差异，HyBNAR小鼠可作为一种便捷的非灵长类前临床模型，用于推进人源I型干扰素的相关研究。