What are rare immunological diseases? Exploring the Advantages of C-NKG Severe Immunodeficient Mice

Do you recall the famous "Bubble Boy"? Poor David suffered from Severe Combined Immunodeficiency (SCID), which made him incapable of combatting any bacteria or viruses, forcing him to spend his entire life in a sterile environment. Shortly after his birth, doctors placed him into a sterile bubble, hence the term "Bubble Boy" for people with similar conditions. Today, let's delve deeper into immunodeficiency disorders.

The immune system serves as an organism’s disease defense system that consists of immune organs, immune cells, and immune active substances. These elements work together to enable the immune system to effectively defend against invading pathogens. Under normal circumstances, the immune system can detect various types of pathogens and/or harmful substances and can differentiate these substances from the organism’s own healthy cells and tissues. However, genetic abnormalities can lead to dysregulation of the immune system, resulting in the development of immune system diseases such as Primary Immunodeficiency Diseases (PIDs) and autoimmune diseases, causing abnormalities in the immune system or loss of immune functions. Several of these genetic autoimmune disorders are rare diseases, but these remain worthy of attention for preclinical research towards interventions.

Figure 1. Primary Immunodeficiency Diseases (PIDs) in the Context of the Classic Immune Response ^[1]

Common Variable Immunodeficiency (CVID)

Common Variable Immunodeficiency (CVID) is a primary immunodeficiency disease (PID) characterized by low levels of protective antibodies, an increased risk of infections, and – most notably – by a reduction in immunoglobulins (Ig). Symptoms include heightened sensitivity to foreign invaders, chronic lung diseases, as well as gastrointestinal inflammation and infections. CVID is a lifelong condition associated with defects in immune cells, and the causative genes include ICOS, TACI, and other genes encoding T cell surface proteins and cytokine receptors ^[2].

The inducible T cell co-stimulator (ICOS) factor encoded by the ICOS gene is exclusively expressed on activated T cells. It plays a vital role in intercellular signaling, cell proliferation, germinal center formation, immunoglobulin isotype switching, and memory B cell development. Homozygous loss-of-function mutations in the ICOS gene within T cells can lead to the development of CVID ^[3]. In mice, knockout of Icos results in a phenotype similar to human CVID, including abnormalities in immunoglobulin isotype switching, immunoglobulin levels, T cell-dependent B cell responses, interferon and interleukin levels, lymph node size, and germinal center formation ^[4-5]. These mice are widely used in research related to CVID and studies of the immune system, especially those involving immunoglobulin isotype switching and germinal center formation.

Figure 2. Impaired Primary Antibody Response to T Cell-Dependent Antigens and Germinal Center Formation in Icos-Knockout (Icos-KO) Mice ^[5]

Immune Deficiency 15A/B (IMD15A/B)

Immune Deficiency 15A (IMD15A) and Immune Deficiency 15B (IMD15B) are both primary immunodeficiency diseases (PIDs) caused by mutations in the IKBKB gene. IMD15A is caused by heterozygous mutations in IKBKB and typically manifests later in life, characterized by recurrent respiratory infections and lymphocytopenia. IMD15B, on the other hand, is caused by homozygous mutations in IKBKB and typically presents in infancy. Patients with IMD15B often have low or absent immunoglobulins, and their immune cell differentiation and activation functions are impaired ^[6], leading to life-threatening bacterial, fungal, and viral infections. Currently, there is no effective treatment for either condition, and management primarily involves infection prevention, treatment, and bolstering the maintenance of the immune system.

IKBKB gene encodes the β subunit of IκB kinase (IKK) complex, known as IKK-β, which plays an inhibitory role in NF-κB signaling pathway. The NF-κB pathway is involved in various biological processes, including immune responses, inflammatory reactions, cell apoptosis, tumor development, regulation of cytokines, cell adhesion molecules, immune modulators, growth factors, transcription factors, and growth-regulatory factors. Mutations in IKBKB result in antigen receptor-related activation of T and B cells.

In mice, the loss of Ikbkb gene leads to a more severe phenotype, resulting in embryonic lethality characterized by severe hepatocellular degeneration and increased apoptosis ^[7]. B cell-specific deletion of Ikbkb affects B cell development, leading to a reduced number of mature B cells ^[8]. Similarly, T cell-specific deletion of Ikbkb results in a significant reduction in peripheral CD4⁺ and CD8⁺ T cells, along with lower IgE levels and delayed T cell-dependent antibody responses ^[9]. Moreover, myeloid-specific Ikbkb knockout impairs neutrophil and macrophage chemotaxis and neutrophil recruitment ^[10].

Figure 3. T Cell-Specific Ikbkb (Ikk2) Conditional Knockout (cKO) Mice Lack Regulatory and Memory T Cells ^[9]

The CHUK gene encodes IκB kinase complex alpha subunit (IKK-α). Mutations in this gene can lead to two severe developmental disorders: Fetal Encasement Syndrome (FES) and Bartsocas-Papas Syndrome Type 2 (BPS2).

FES is characterized by severe fetal malformations, including craniofacial abnormalities, elliptical deformities, and limbs that are poorly developed, wrapped in abnormal, translucent, membranous skin that lacks elasticity. BPS2 is characterized by skin webbing of one or more joints, cleft lip and/or palate, finger deformities, and genital malformations.

Studies have shown that Chuk knockout (KO) mice exhibit a perinatal lethal phenotype and a bottle-like body shape. Their limbs and tail are wrapped in thick, sticky epidermal tissue. Additionally, these mice may display skeletal abnormalities, developmental eye and conjunctival abnormalities, and embryonic vascular development abnormalities, similar to the phenotype seen in human FES disease ^[11-13]. Furthermore, these mice also exhibit immunodeficiency, including abnormalities in B cell number and function ^[14].

Figure 4. Severe Embryonic and Skeletal Developmental Defects in Chuk-Knockout (Chuk-KO) Mice ^[14]

Cyagen Rare Disease Research Resources - Gene-Edited Mice

Gene-edited mouse models play a crucial role in studying the mechanisms of rare diseases and evaluating drug development. Cyagen has thousands of self-developed gene-edited mouse strains, including various gene knockout and conditional knockout rare disease mouse models, covering genes such as ICOS, AIRE, ITK, and IKBKB. Additionally, we offer specialized customized services tailored to your research needs, accelerating your research projects.

Rare Disease Data Center

The Rare Disease Data Center (RDDC) is hosted and developed by the Rare Disease Gene Therapy Alliance under the leadership of Artificial Intelligence Innovation Center at the Tsinghua University and Pearl River Delta Research Institute. With the biological and genetic technology support provided by Cyagen, it has undergone upgrades from version 1.0 to 2.0. This database offers information on various rare diseases and aims to better serve researchers' needs for data querying and data mining.

After login, users can swiftly progress from target gene discovery to querying the phenotypes and functions of these target genes. Additionally, they can also select the most relevant animal models based on the phenotypes associated with the target genes. This streamlined process enables researchers to rapidly formulate research strategies and embark on scientific investigations and drug discovery efforts targeting disease-causing genes.

C-NKG Severe Immunodeficient Mice at Cyagen

C-NKG mice are a severe immunodeficient strain developed by Cyagen through knockout of the Il2rg gene on the NOD-Scid background strain. These models are currently recognized as an ideal model for research in areas such as cancer, immune function, autoimmune diseases, immunotherapy, infectious disease/vaccines, graft versus host disease (GvHD), safety assessment, and stem cell biology. Additionally, Cyagen can provide services tailored to your project requirements, including human immune system reconstitution and xenotransplantation of human tumor cell lines.

References:

[1]Novodvorsky, P., & Allahabadia, A. (2017). Thyrotoxicosis. Medicine, 45(12), 766-773. 

[2]Peng XP, Caballero-Oteyza A, Grimbacher B. Common Variable Immunodeficiency: More Pathways than Roads to Rome. Annu Rev Pathol. 2023 Jan 24;18:283-310. 

[3]Yong PF, Salzer U, Grimbacher B. The role of costimulation in antibody deficiencies: ICOS and common variable immunodeficiency. Immunol Rev. 2009 May;229(1):101-13.

[4]McAdam AJ, Greenwald RJ, Levin MA, Chernova T, Malenkovich N, Ling V, Freeman GJ, Sharpe AH. ICOS is critical for CD40-mediated antibody class switching. Nature. 2001 Jan 4;409(6816):102-5. 

[5]Tafuri A, Shahinian A, Bladt F, Yoshinaga SK, Jordana M, Wakeham A, Boucher LM, Bouchard D, Chan VS, Duncan G, Odermatt B, Ho A, Itie A, Horan T, Whoriskey JS, Pawson T, Penninger JM, Ohashi PS, Mak TW. ICOS is essential for effective T-helper-cell responses. Nature. 2001 Jan 4;409(6816):105-9.

[6]National Center for Biotechnology Information. (n.d.). Severe combined immunodeficiency due to IKK2 deficiency. 

[7]Li Q, Estepa G, Memet S, Israel A, Verma IM. Complete lack of NF-kappaB activity in IKK1 and IKK2 double-deficient mice: additional defect in neurulation. Genes Dev. 2000 Jul 15;14(14):1729-33. 

[8]Pasparakis M, Schmidt-Supprian M, Rajewsky K. IkappaB kinase signaling is essential for maintenance of mature B cells. J Exp Med. 2002 Sep 16;196(6):743-52. 

[9]Schmidt-Supprian M, Courtois G, Tian J, Coyle AJ, Israël A, Rajewsky K, Pasparakis M. Mature T cells depend on signaling through the IKK complex. Immunity. 2003 Sep;19(3):377-89.

[10] Penzo M, Molteni R, Suda T, Samaniego S, Raucci A, Habiel DM, Miller F, Jiang HP, Li J, Pardi R, Palumbo R, Olivotto E, Kew RR, Bianchi ME, Marcu KB. Inhibitor of NF-kappa B kinases alpha and beta are both essential for high mobility group box 1-mediated chemotaxis [corrected]. J Immunol. 2010 Apr 15;184(8):4497-509.

[11] Hu Y, Baud V, Delhase M, Zhang P, Deerinck T, Ellisman M, Johnson R, Karin M. Abnormal morphogenesis but intact IKK activation in mice lacking the IKKalpha subunit of IkappaB kinase. Science. 1999 Apr 9;284(5412):316-20. 

[12] Takeda K, Takeuchi O, Tsujimura T, Itami S, Adachi O, Kawai T, Sanjo H, Yoshikawa K, Terada N, Akira S. Limb and skin abnormalities in mice lacking IKKalpha. Science. 1999 Apr 9;284(5412):313-6.

[13] Li Q, Lu Q, Hwang JY, Büscher D, Lee KF, Izpisua-Belmonte JC, Verma IM. IKK1-deficient mice exhibit abnormal development of skin and skeleton. Genes Dev. 1999 May 15;13(10):1322-8. 

[14] Enzler T, Bonizzi G, Silverman GJ, Otero DC, Widhopf GF, Anzelon-Mills A, Rickert RC, Karin M. Alternative and classical NF-kappa B signaling retain autoreactive B cells in the splenic marginal zone and result in lupus-like disease. Immunity. 2006 Sep;25(3):403-15.