The IL15 gene encodes a pleiotropic four-α-helix bundle cytokine known as Interleukin-15 (IL-15), which is essential for the development, survival, and activation of immune cells, particularly Natural Killer (NK) cells and memory CD8+ T cells. Unlike many cytokines, IL-15 is primarily regulated at the post-transcriptional and translational levels rather than just transcriptionally, and it is uniquely delivered to target cells through trans-presentation, where it is shuttled to the cell surface bound to its high-affinity receptor, IL-15Rα ^[1]. The protein is widely expressed across a variety of tissues, including the placenta, skeletal muscle, kidney, lung, and heart, and is produced by both hematopoietic cells (such as monocytes, macrophages, and dendritic cells) and non-hematopoietic cells (such as epithelial cells and fibroblasts) ^[2]. Functionally, IL-15 triggers the JAK/STAT (specifically JAK1/3 and STAT3/5) and PI3K/AKT/mTOR signaling pathways to promote cellular proliferation and inhibit apoptosis by upregulating anti-apoptotic factors like BCL2 ^[3]. Because of its potent inflammatory effects, dysregulation of the IL15 gene is implicated in several pathologies: over-expression is strongly associated with autoimmune diseases like Celiac disease, Rheumatoid Arthritis, and Multiple Sclerosis, as well as certain malignancies like Adult T-cell Leukemia, while its deficiency can lead to severe immunodeficiency or impaired response to viral infections ^[4]. The B6-huIL15 mouse is a humanized model constructed through gene-editing technology, in which the region from partial intron 4 to TGA stop codon of mouse Il15 is replaced with the region from partial intron 4 to TGA stop codon of human IL15. This model can be used for research on autoimmune diseases like Celiac disease, Rheumatoid Arthritis, and Multiple Sclerosis, as well as certain malignancies like Adult T-cell Leukemia. Furthermore, it serves as a platform for the screening, development, and preclinical evaluation of IL15-targeted therapeutics.

NKG mice are a type of severe immunodeficient mouse developed by Cyagen by deleting the Il2rg gene from the NOD-Scid strain. This strain lacks mature T, B, and NK cells, has reduced complement activity, and weak macrophage phagocytosis of human cells. As a result, NKG mice can efficiently engraft human hematopoietic stem cells (HSC), peripheral blood mononuclear cells (PBMC), patient-derived xenografts (PDX), or adult stem cells and tissues. In the field of immunology research, there are differences between humans and mice in terms of physiology and immune systems, so research conducted directly on mice cannot fully reflect the human situation. By transplanting human peripheral blood mononuclear cells (PBMC) or human hematopoietic stem cells (HSC) into immunodeficient mice, the mouse’s immune system is partially or completely replaced by the human immune system, allowing for the simulation of human immune system function in vivo and providing an effective model for studying the human immune system. However, due to the lack of cytokine necessary for human NK cell development in mice, there are also differences between humans and mice in the relevant regulatory factors. When reconstructing the human immune system in severely immunodeficient mice, the proportion of reconstructed NK cells is relatively low, which is not conducive to drug development targeting NK cells. Interleukin-15 (IL-15) is a cytokine that regulates the activation and proliferation of T cells and natural killer (NK) cells. It also plays a role in balancing the number of CD8+ memory cells alongside IL-2. Research indicates that IL-15 is essential for the differentiation, function, and survival of NK cells. Providing sufficient human IL-15 can help stabilize the function of human NK cells within a mouse model ^[1-2]. The NKG-hIL15 mice are constructed by knocking in the human IL15 gene from the NKG mice. Compared to NKG mice, NKG-hIL15 mice significantly enhance the reconstitution proportion of human NK cells after HSC or PBMC transplantation. These mice can be utilized for the development of immunotherapies targeting NK cells and drug evaluation.

Pdgfrb is located on chromosome 18 of mice. Nuclease Technology was used to design sgRNA; Pdgfrb knockout mice were obtained by applying high-throughput electroporation of fertilized eggs. After sexual maturity, sperm were collected for cryopreservation.

Smad2 is located on chromosome 18 of mice. SgRNA and ssDNA were designed using Nuclease Technology; Smad2 conditional knockout mice were obtained by high-throughput electroporation of fertilized eggs. After sexual maturity, sperm were collected for cryopreservation.