Enhanced Antibody Responses in a Novel NOG Transgenic Mouse with Restored Lymph Node Organogenesis.

Takeshi Takahashi,Hayato Abe,Fumihiro Sugiyama,Ryoji Ito,Kenji Kawai,Seiya Mizuno,Mamoru Ito,Motohito Goto,Ikumi Katano

doi:10.3389/fimmu.2017.02017

Abstract

Lymph nodes (LNs) are at the center of adaptive immune responses. Various exogenous substances are transported into LNs and a series of immune responses ensue after recognition by antigen–specific lymphocytes. Although humanized mice have been used to reconstitute the human immune system, most lack LNs due to deficiency of the interleukin (IL)-2Rγ gene (cytokine common γ chain, γc). In this study, we established a transgenic strain, NOG-pRORγt-γc, in the NOD/shi-scid-IL-2Rγnull (NOG) background, in which the γc gene was expressed in a lymph-tissue inducer (LTi) lineage by the endogenous promoter of RORγt. In this strain, LN organogenesis was normalized and the number of human T cells substantially increased in the periphery after reconstitution of the human immune system by human hematopoietic stem cell transplantation. The distribution of human T cells differed between NOG-pRORγt-γc Tg and NOG-non Tg mice. About 40% of human T cells resided in LNs, primarily the mesenteric LNs. The LN-complemented humanized mice exhibited antigen-specific immunoglobulin G responses together and an increased number of IL-21+–producing CD4+ T cells in LNs. This novel mouse strain will facilitate recapitulation of human immune responses.

Highlights

Reconstitution of the human immune system in immunodeficient mice enables investigation of human immunology and facilitates drug discovery [1,2,3]
Because RORγt is the critical master transcription factor for lineage specification, we generated a bacterial artificial chromosome (BAC) transgenic strain in which expression of the γc gene was regulated by the endogenous control elements of the RORγt locus (Figure S1 in Supplementary Material)
Transgenic expression of the γc gene in the lymph-tissue inducer (LTi)-lineage restored lymph nodes (LNs) development, which was absent in γc KO mice (Figure 1)

Summary

Introduction

Reconstitution of the human immune system in immunodeficient mice enables investigation of human immunology and facilitates drug discovery [1,2,3]. Progress in humanized mouse technology relies on extremely immunodeficient mouse strains; e.g., NOD-scid [4], NOD/Shi-scid IL2rγnull (NOG) [5], NOD/LtSz-scid IL2rγnull (NSG) [6], and BALB/c Rag2nullIL2rγnull (BRG) [7]. These platform strains are characterized by a severe deficiency in the murine immune system. In addition to deficiency of B and T lymphocytes due to scid gene mutation or disruption of the RAG-2 gene, especially, it is deletion of the interleukin (IL)-2 receptor γ (γc) gene that compromises the entire murine immune system. There are indirect secondary effects; e.g., impaired development of lymph nodes (LNs) in γc-deficient mice [11]

Methods

Results

Conclusion