Proprotein convertase subtilisin/kexin 9 (PCSK9) is a serine protease primarily produced in the liver but expressed in other tissues, including the intestine, heart, and neurons. The N-terminal domain of the PCSK9 protein is responsible for protein localization and stability, while the C-terminal domain is responsible for protein enzymatic activity ^[1]. The Low-density lipoprotein receptor (LDLR) is a receptor that is responsible for clearing low-density lipoprotein cholesterol (LDL-C) from the blood. PCSK9 cleaves the intracellular domain of LDLR on the cell surface, causing it to detach from the cell membrane and be transported to the lysosome for degradation, promoting LDLR degradation, and increasing plasma LDL-C. Overexpression or gain-of-function mutations of the PCSK9 gene can lead to LDL-C accumulation by reducing LDLR levels. This can cause hypercholesterolemia, which increases the risk of cardiovascular diseases, such as atherosclerosis and coronary heart disease, and neurodegenerative diseases, such as Alzheimer's disease ^[2]. PCSK9 has become an important target for the development of lipid-lowering drugs. Several PCSK9-targeted antibodies or small nucleic acid drugs have been approved for marketing worldwide, including evolocumab from Amgen, alirocumab from Sanofi and Regeneron, and inclisiran from Novartis. These drugs primarily work by inhibiting PCSK9 activity or preventing PCSK9 protein from binding to LDLR, lowering LDL-C levels in the blood to treat hypercholesterolemia ^[3-4]. In addition, PCSK9 can promote tumor growth and development by regulating cell proliferation, migration, and invasion. It can also regulate the expression of inflammatory factors that contribute to inflammation. Therefore, targeting the expression of PCSK9 has been investigated in tumor immunotherapy and autoimmune disease therapy ^[5-6]. B6-hPCSK9 mice are a humanized model generated by gene editing technology to replace the mouse Pcsk9 gene with the human PCSK9 gene sequence. These mice express human PCSK9 protein and can be used for research on various metabolic diseases, neurodegenerative diseases, tumor development, autoimmune disease mechanisms, and for the preclinical pharmacological evaluation of PCSK9-targeted drugs. In addition, Cyagen has developed a similar model, the B6-hPCSK9(CDS) mouse (PCSK9 coding sequence humanized model, Catalog Number: C001593). Compared to the B6-hPCSK9 mouse model, the B6-hPCSK9(CDS) mouse expresses higher levels of human PCSK9 and exhibits LDLR protein expression closer to physiological levels. It is recommended to choose the appropriate model based on the type of drug or research direction.

Lipoprotein A (LPA) is a type of particle similar to low-density lipoprotein (LDL) that is considered one of the risk factors for cardiovascular disease (CVD), such as atherosclerosis, coronary heart disease, stroke, etc ^[1]. LP(a) is similar in size and lipid content to LDL (low-density lipoprotein) and also contains the lipoprotein ApoB-100. However, unlike LDL, LP(a) additionally contains a variable-length lipoprotein called Apo(a), which covalently binds to ApoB-100 through a single disulfide bond. LP(a) plays an important role in systemic lipid transport, guiding inflammatory cells into blood vessel walls and leading to smooth muscle cell proliferation. Furthermore, it is involved in wound healing and tissue repair, interacting with the components of blood vessel walls and the extracellular matrix ^[2]. However, LP(a) can also cause arterial narrowing by adhering to the arterial wall, accelerating the formation of blood clots, and thereby triggering a series of pathological changes related to coronary heart disease, cardiovascular disease, atherosclerosis, thrombus formation, and stroke ^[3]. The plasma concentration of LP(a) is closely related to genetic factors and is primarily regulated by the LPA gene. Therefore, the LPA gene is an important potential target for cardiovascular disease treatment. The LPA gene encodes a serine protease that inhibits the activity of tissue-type plasminogen activator I. Fragments of this protein, generated through protein hydrolysis, can adhere to atherosclerotic lesions in arteries, promoting blood clot formation. The LPA gene is expressed in both humans and non-human primates but is not expressed in mice. Constructing mouse models expressing the human LPA gene is of significant importance for developing lipid-lowering drugs, which can drive the development of novel therapies for cardiovascular diseases. Currently, various novel therapies targeting the transcription rate of the LPA gene are under development, including small interfering RNA (siRNA) and antisense oligonucleotides (ASO) ^[4]. Proprotein convertase subtilisin/kexin 9 (PCSK9) is a serine protease primarily produced in the liver but expressed in other tissues, including the intestine, heart, and neurons. The N-terminal domain of the PCSK9 protein is responsible for protein localization and stability, while the C-terminal domain is responsible for protein enzymatic activity ^[5]. The Low-density lipoprotein receptor (LDLR) is a receptor that is responsible for clearing low-density lipoprotein cholesterol (LDL-C) from the blood. PCSK9 cleaves the intracellular domain of LDLR on the cell surface, causing it to detach from the cell membrane and be transported to the lysosome for degradation, promoting LDLR degradation, and increasing plasma LDL-C. Overexpression or gain-of-function mutations of the PCSK9 gene can lead to LDL-C accumulation by reducing LDLR levels. This can cause hypercholesterolemia, which increases the risk of cardiovascular diseases, such as atherosclerosis and coronary heart disease, and neurodegenerative diseases, such as Alzheimer's disease ^[6]. PCSK9 has emerged as a key target for the development of lipid-lowering drugs. Several PCSK9-targeted antibodies or small nucleic acid drugs have been approved for marketing worldwide, including evolocumab from Amgen, alirocumab from Sanofi and Regeneron, and inclisiran from Novartis. These drugs primarily work by inhibiting PCSK9 activity or preventing PCSK9 protein from binding to LDLR, lowering LDL-C levels in the blood to treat hypercholesterolemia ^[7-8]. In addition, PCSK9 can promote tumor growth and development by regulating cell proliferation, migration, and invasion. It can also regulate the expression of inflammatory factors that contribute to inflammation. Therefore, targeting the expression of PCSK9 has been investigated in tumor immunotherapy and autoimmune disease therapy ^[9-10]. The B6-hLPA (CKI)/Alb-cre/hPCSK9 mouse model is generated by crossing B6-hLPA (CKI) mice (Catalog No.: C001521, a mouse strain with conditional expression of the human LPA gene), Alb-Cre mice (liver-specific Cre-expressing mice), and B6-hPCSK9 mice (Catalog No.: C001617). This model harbors two cardiovascular disease risk factors, namely Lp (a) (lipoprotein (a)) and PCSK9, making it suitable for research on hyperlipidemia, stroke, coronary heart disease, and other atherosclerotic cardiovascular diseases (ASCVD).

Lipoprotein(a) (LP(a)) is considered one of the risk factors for atherosclerosis, coronary heart disease, stroke, and other cardiovascular diseases (CVD) ^[1]. It is similar in size and lipid content to low-density lipoprotein (LDL) and contains the lipoprotein ApoB-100, but also includes a variable-length lipoprotein(a) (Apo(a)), which is covalently bound to ApoB-100 via a single disulfide bond. LP(a) plays an important role in systemic lipid transport, guiding inflammatory cells into the vascular wall and causing smooth muscle cell proliferation. In addition, it is also involved in wound healing and tissue repair, interacting with components of the vascular wall and extracellular matrix ^[2]. LP(a) can also cause arterial narrowing by attaching to the arterial wall, accelerating the formation of blood clots, and leading to a series of pathological changes ^[3]. The plasma concentration of LP(a) is closely related to genetic factors and is mainly regulated by the LPA gene. Therefore, the LPA gene is an important potential target for treating cardiovascular disease. The LPA gene is expressed in humans and non-human primates but not mice. By crossing mice conditional expression of human LPA (LSL-hLPA) with liver-specific Cre expression mice (Alb-Cre) that specifically overexpress the human LPA gene in the liver can be obtained. ApoB is a protein that plays a central role in lipid metabolism and cardiovascular disease (CVD) and is responsible for transporting cholesterol and other fat molecules to all tissues throughout the body ^[4]. The accumulation of cholesterol and other lipids can promote the formation of arterial plaques, leading to arterial narrowing and reduced blood flow, increasing the risk of cardiovascular events such as myocardial infarction and stroke ^[5]. Therefore, high levels of ApoB are a major risk factor for plaque in cardiovascular diseases such as atherosclerosis. ApoB100 is the most abundant subtype of ApoB in humans and the most important subtype of ApoB in cardiovascular disease (CVD) ^[6]. Mice overexpressing the human APOB gene have significantly elevated LDL cholesterol in serum. The B6-RCL-hLPA/Alb-cre/TG(APOB) mice express human LP(a) and ApoB, two risk factors for cardiovascular disease. It can be used in the study of hyperlipidemia, stroke, coronary heart disease, familial hypercholesterolemia (FH), and other atherosclerotic cardiovascular diseases (ASCVD). Internal data (not shown) indicates that, compared to the Cyagen strain B6-LPA(CKI)/Alb-Cre&Tg(APOB) mice (Catalog No. C001494), this model exhibits a more stable expression of human LPA protein at different ages. Please choose the model based on the experimental need for continuous stability of human LPA protein expression.

The gene TNFRSF13C encodes the B cell-activating factor receptor (BAFF-R), also known as BLyS receptor 3 (BR3) or CD268. As a member of the tumor necrosis factor receptor superfamily (TNFRSF), BAFF-R functions as a crucial type III transmembrane signaling protein on lymphocytes. Its expression is predominantly observed on the surface of B cells throughout various stages of their development, from transitional to mature naive and memory populations, underscoring its vital role in peripheral B cell homeostasis ^[1]. BAFF-R serves as the primary receptor for the cytokine BAFF (TNFSF13B), and their interaction delivers essential survival and maturation signals to B cells, mediated through downstream pathways including the activation of NF-κB and PI3K. Genetic alterations in TNFRSF13C, including point mutations and deletions, or dysregulation of the BAFF-BAFF-R axis, are increasingly recognized for their contribution to immune pathology ^[2]. Such aberrations are associated with primary immunodeficiencies like common variable immunodeficiency (CVID), characterized by profound defects in antibody production and recurrent infections, as well as a range of autoimmune diseases such as systemic lupus erythematosus (SLE) and Sjögren's syndrome, and certain B cell malignancies ^[2-3]. The critical, non-redundant function of BAFF-R in B cell biology highlights its significance as a key node in adaptive immunity and positions the BAFF-BAFF-R pathway as a compelling target for therapeutic intervention in a spectrum of immune-mediated disorders. The B6-hBAFFR (hTNFRSF13C) mouse is a humanized model constructed by replacing the sequence of the mouse Tnfrsf13c endogenous extracellular domain in situ with the corresponding extracellular domain from the human TNFRSF13C. The B6-hBAFFR (hTNFRSF13C) mice can be used for the study of the pathogenesis of immune-mediated disorders such as common variable immunodeficiency (CVID), systemic lupus erythematosus (SLE), and Sjögren's syndrome, and certain B cell malignancies, as well as for TNFRSF13C-targeted drug development.

Interleukin-13, encoded by the IL13 gene, is a key type 2 immune response cytokine, predominantly expressed by activated Th2 helper T cells, type 2 innate lymphoid cells (ILC2s), and mast cells, and central to type 2 immune responses elicited by allergens or other stimuli ^[1]. The IL-13 protein, a ~13 kDa molecule with a four-helix bundle structure, mediates its biological effects by binding to the cell surface receptor IL-13Rα1 and recruiting the IL-4Rα chain to form a functional receptor complex, thereby activating the downstream JAK/STAT6 signaling pathway ^[2]. Key functions of IL-13 include promoting B cell maturation and plasma cell differentiation, inducing IgE isotype switching, and suppressing the pro-inflammatory activity of macrophages, leading to reduced production of pro-inflammatory cytokines and chemokines ^[3]. Furthermore, IL-13 induces goblet cell hyperplasia, promotes mucus secretion, and contributes to airway remodeling and fibrosis ^[4]. Numerous studies have established the critical role of IL-13 in the pathogenesis of various diseases, including asthma, allergic rhinitis, atopic dermatitis, and eosinophilic esophagitis ^[1-4]. Consequently, targeting IL-13 and its signaling pathways has become a significant therapeutic strategy for these conditions; for example, the monoclonal antibody Dupilumab, which simultaneously blocks IL-4 and IL-13 signaling, has demonstrated substantial efficacy in treating diverse type 2 inflammation-related diseases ^[5]. Thus, IL-13 represents a promising therapeutic target for allergic and inflammatory disorders. The IL23A gene encodes the p19 subunit, a component of interleukin-23 (IL-23), which forms a heterodimer with the p40 subunit (encoded by IL12B) to generate the functional IL-23 cytokine. Primarily expressed by activated dendritic cells, macrophages, and monocytes, IL-23 signals through the IL-23 receptor (IL-23R) complex, activating the JAK-STAT pathway to promote Th17 cell differentiation and maintain IL-17 production. This process drives inflammatory responses and mucosal immunity against extracellular pathogens ^[6-7]. Genetic polymorphisms within IL23A are strongly associated with autoimmune and inflammatory diseases, including psoriasis, Crohn's disease, and inflammatory bowel disease, due to dysregulated Th17 activity and chronic inflammation ^[6-7]. Monoclonal antibodies targeting IL-23, such as risankizumab and guselkumab, selectively block the p19 subunit, demonstrating therapeutic efficacy in psoriasis and inflammatory bowel diseases by suppressing pathogenic IL-17/Th17 pathways ^[8]. While IL-23 plays a role in protective immunity, its overactivation contributes to tissue damage in autoimmune settings, highlighting its dual function in immune regulation and disease pathogenesis ^[6-9]. B6-hIL13/hIL23A mice are humanized models generated by crossing B6-hIL13 mice (Product No.: C001634) with B6-hIL23A mice (Product No.: C001618). These mice are suitable for studying the pathological mechanisms and therapeutic strategies of allergic and inflammatory diseases, immune-related disorders, and cancer, as well as for the screening, development, and preclinical evaluation of IL13/IL23A-targeted drugs.

Thymic stromal lymphopoietin (TSLP), an interleukin-7 (IL-7) family cytokine, is encoded by the TSLP gene and is predominantly produced by epithelial cells. Its expression is notably upregulated by environmental cues, including allergens and proteases, positioning it as a sentinel at the interface of environmental exposure and immune activation ^[1-2]. Secreted by a range of cell types, such as epithelial cells, keratinocytes, mast cells, and dendritic cells, TSLP is critical in the initiation of immune responses, primarily through the activation of dendritic cells and subsequent polarization of T helper type 2 (Th2) cell differentiation. This process has broad implications for diverse immune cell populations and B cell functions relevant to allergic inflammation ^[2]. Transcriptional regulation of TSLP gene expression is tightly controlled by factors including NF-κB and AP-1, with genetic polymorphisms within the TSLP locus being strongly implicated in asthma susceptibility ^[1-3]. Dysregulated TSLP signaling is now recognized as a pivotal factor in the pathogenesis of atopic disorders, encompassing conditions such as atopic dermatitis, asthma, allergic rhinitis, and eosinophilic esophagitis ^[1-4]. For example, tezepelumab, a monoclonal antibody that blocks the TSLP signaling pathway, has demonstrated significant efficacy in clinical trials for patients with severe asthma, reducing acute exacerbations and improving lung function ^[4]. Consequently, TSLP is under intense investigation as a therapeutic target, with current strategies focusing on disrupting its signaling pathways to modulate allergic and inflammatory diseases ^[5]. The B6-hTSLP mouse is a humanized model constructed using gene editing technology, where the mouse Tslp endogenous domain was replaced with the human TSLP domain . The murine signal peptide was preserved. This model can be used for studying the pathological mechanisms and therapeutic approaches of allergic and inflammatory diseases and for the development of TSLP-targeted drugs.

The Growth Differentiation Factor 15 (GDF15) gene encodes a secreted ligand of the Transforming Growth Factor-β (TGF-β) superfamily protein. This protein plays a crucial role in the TGFβ signaling pathway, which is integral to various cellular processes ^[1]. GDF15 is involved in the body’s response to stress following cell damage. It is associated with tissue hypoxia, inflammation, acute injury, and oxidative stress, among other disease states. Elevated levels of GDF15 in the serum are considered a potential biomarker for the progression of cancer, as it is overexpressed in various types of tumor cells, including colon, prostate, pancreatic, breast, and thyroid cancers ^[2-3]. Interestingly, GDF15 is not solely a pathological biomarker. Despite its association with disease states, it also exhibits high expression under various non-pathological conditions. Studies suggest that GDF15 may exert a protective effect on the heart, liver, kidney, and lungs following inflammation and injury, highlighting its potential role in tissue repair and recovery ^[4]. GDF15 is an important biomarker for metabolic diseases, cardiovascular diseases, tumors, and more, and holds potential as a therapeutic target. It can induce anorexia by activating the GFRAL-RET receptor in the brainstem, making it a promising target for anti-obesity therapy ^[5]. Furthermore, GDF15 neutralization could potentially alleviate anorexia and weight loss, common side effects of platinum-based chemotherapy ^[6]. Research has shown that a therapeutic antagonistic monoclonal antibody can inhibit RET signal transduction by blocking the interaction between GDF15-driven RET and cell surface GFRAL. This could reverse excessive lipid oxidation in tumor-bearing mice and prevent cancer cachexia ^[7]. The potential of GDF15 as a therapeutic target is being increasingly recognized in the scientific community. In this context, the construction of animal gene humanization models for this target is of significant importance, providing a crucial tool for further research and development in this area. This strain is a mouse Gdf15 gene humanized model expressing human GDF15 protein obtained by replacing the sequence encoding the endogenous structural domain in the mouse Gdf15 gene with the sequence encoding the structural domain in the human GDF15 gene. B6-hGDF15 mice can be used for research on metabolic diseases, cardiovascular diseases, tumor occurrence and development, etc., to assist in the preclinical evaluation of GDF15-targeted drugs.

The Insulin-like Growth Factor 1 Receptor (IGF-1R), encoded by the IGF1R gene, is a receptor tyrosine kinase expressed in most tissues and cells. Its expression is developmentally regulated and influenced by nutrition, hormones, and intracellular factors, with high expression during growth and development, declining in adulthood ^[1]. The IGF1R protein is a heterotetramer (α2β2) of α and β subunits derived from a precursor protein, forming transmembrane αβ chains. The α chain is located extracellularly, while the β chain spans the cell membrane and is responsible for intracellular signal transduction after ligand stimulation. IGF1R binds Insulin-like Growth Factor-1 (IGF-1) with high affinity, mediating IGF-1's growth-promoting effects and regulating cell growth, differentiation, survival, and metabolism ^[1-4], and IGF1R defects are linked to growth retardation and diabetes ^[2-4]. Furthermore, IGF1R overexpression in tumors promotes proliferation, invasion, and metastasis, making it a cancer therapy target ^[3]. In thyroid eye disease (TED), an autoimmune disorder, activating IGF1R antibodies can be detected. IGF1R is overexpressed in T cells, B cells, and orbital fibroblasts of patients, forming a signal transduction complex with the thyroid-stimulating hormone receptor, thereby enhancing the effect of thyroid-stimulating hormone ^[5]. Therefore, Targeting IGF1R to inhibit thyroid-stimulating hormone action is a therapeutic strategy for TED, improving exophthalmos ^[6]. B6-hIGF1R mice are humanized models generated using gene editing technology by integrating the protein-coding sequence (CDS) encoding the extracellular domain of human IGF1R protein and the intracellular domain of mouse IGF1R protein into the mouse Igf1r gene locus, while retaining the endogenous gene sequence encoding the signal peptide of mouse IGF1R protein. Homozygous B6-hIGF1R mice are viable and fertile, and can be used for studying the pathological mechanisms and treatments of growth retardation, diabetes, and cancer, as well as for screening, developing, and preclinical efficacy and safety evaluation of IGF1R-targeted drugs.

The TNFSF4 gene (tumor necrosis factor superfamily member 4, also known as OX40L) encodes the OX40 ligand protein, a type II transmembrane protein mainly expressed on antigen-presenting cells (APCs, such as dendritic cells, B cells, and macrophages), as well as endothelial cells and smooth muscle cells ^[1]. This protein binds to the receptor OX40 (TNFRSF4) on the surface of T cells, providing crucial co-stimulatory signals that enhance T-cell proliferation, survival, and cytokine secretion, thereby playing a central role in adaptive immunity and inflammatory responses ^[2]. Dysregulated expression of TNFSF4 is associated with various autoimmune diseases, such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), and its gene polymorphisms have been proven to be related to disease susceptibility ^[3]. Altering the OX40-OX40L interaction can either enhance the immune response to fight cancer or suppress it to treat autoimmune diseases ^[4]. Blocking the OX40-OX40L binding may alleviate autoimmune diseases by reducing the levels of pro-inflammatory cytokines and enhancing the function of regulatory T cells. Due to its crucial role in immune regulation, OX40L is regarded as an important target for treating autoimmune diseases and cancer immunotherapy, and current drug development focuses on monoclonal antibodies and OX40L inhibitors. B6-hOX40L (hTNFSF4) mice are a humanized model constructed by using gene editing technology to replace the endogenous extracellular domain of the mouse Tnfsf4 gene with the extracellular domain of the human TNFSF4 gene. This model can be used for research on autoimmune diseases (such as systemic lupus erythematosus and rheumatoid arthritis), cancer immunology, and TNFSF4-targeted drug development.

TNF-like ligand 1A (TL1A), also known as TNF superfamily member 15 (TNFSF15), is a member of the tumor necrosis factor (TNF) family encoded by the TNFSF15 gene in humans. TL1A acts as a ligand for death receptor 3 (DR3) and decoy receptor 3 (DcR3), providing a stimulatory signal for downstream pathways. It regulates the proliferation, activation, and apoptosis of effector cells, as well as cytokine and chemokine production. TL1A is expressed in various immune cells, including monocytes, macrophages, dendritic cells, and T cells, as well as in non-immune cells such as synovial fibroblasts and endothelial cells. It plays a crucial role in modulating immune responses by promoting the differentiation and survival of T cells, particularly Th17 cells involved in inflammatory processes ^[1]. TL1A enhances IL-2 responses in anti-CD3/CD28-stimulated T cells and synergizes with IL-12 and IL-18 to augment IFN-γ release in human T and NK cells, biasing T cell differentiation toward a Th1 phenotype ^[2]. Dysregulation of TL1A expression is implicated in autoimmune diseases, including inflammatory bowel disease (IBD), rheumatoid arthritis (RA), primary biliary cholangitis (PBC), systemic lupus erythematosus (SLE), and ankylosing spondylitis (AS) ^[1]. TL1A has emerged as a promising therapeutic target, with ongoing research focused on developing monoclonal antibodies and other biologics to neutralize TL1A and reduce inflammation in autoimmune disorders. Clinical trial results suggest that TL1A inhibition can be used in the treatment of various autoimmune diseases, particularly IBD ^[3-5]. The IL23A gene encodes the p19 subunit, a component of interleukin-23 (IL-23), which forms a heterodimer with the p40 subunit (encoded by IL12B) to generate the functional IL-23 cytokine ^[1]. Primarily expressed by activated dendritic cells, macrophages, and monocytes, IL-23 signals through the IL-23 receptor (IL-23R) complex, activating the JAK-STAT pathway to promote Th17 cell differentiation and maintain IL-17 production. This process drives inflammatory responses and mucosal immunity against extracellular pathogens ^[6-7]. Genetic polymorphisms within IL23A are strongly associated with autoimmune and inflammatory diseases, including psoriasis, Crohn's disease, and inflammatory bowel disease, due to dysregulated Th17 activity and chronic inflammation ^[6-7]. Monoclonal antibodies targeting IL-23, such as risankizumab and guselkumab, selectively block the p19 subunit, demonstrating therapeutic efficacy in psoriasis and inflammatory bowel diseases by suppressing pathogenic IL-17/Th17 pathways ^[8]. While IL-23 plays a role in protective immunity, its overactivation contributes to tissue damage in autoimmune settings, highlighting its dual function in immune regulation and disease pathogenesis ^[6-9]. B6-hTL1A/hIL23A mice are humanized models generated by crossing B6-hTL1A (TNFSF15) mice (Catalog No.: C001603) with B6-hIL23A mice (Catalog No.: C001618). These mice are suitable for studying the pathological mechanisms and therapeutic strategies of allergic and inflammatory diseases, immune-related disorders, and cancer, as well as for the screening, development, and preclinical evaluation of TL1A/IL23A-targeted drugs.