B6-hIL-17A Mice

Catalog Number: C001510

Strain Name: C57BL/6NCya-Il17a^tm1(hIL17A)/Cya

Genetic Background: C57BL/6NCya

Reproduction: Homozygote x Homozygote

Strain Description

Interleukin 17A (IL-17A) is a signature cytokine of the T helper 17 (Th17) subset of CD4+ T cells and one of the six members (IL-17A~IL-17F) of the IL-17 family. IL-17A is primarily produced by Th17 cells and can also be produced by other immune cells under certain conditions, including CD8+ T cells, γδT cells, natural killer T (NKT) cells, monocytes, neutrophils, and microglia ^[1]. IL-17A mediates downstream pathways that induce the production of inflammatory molecules, chemokines, antimicrobial peptides, and remodeling proteins, which have important effects on host defense, cell transport, immune regulation, and tissue repair, especially in inducing innate immune defense. In healthy skin, commensal microorganisms induce the production of IL-17A to provide antifungal protection. When the skin barrier is damaged, IL-17A promotes epithelial cell proliferation and can clear pathogenic factors, promoting tissue repair and wound healing ^[2]. IL-17A usually protects the body when it is acutely injured, but when a wound requires long-term healing and becomes a chronic injury, the role of IL-17A may transform into wound erosion or excessive proliferation, ultimately leading to loss of function ^[3].

IL-17A plays a key role in various infectious diseases, inflammations, autoimmune diseases, and cancers. Its high expression level is associated with chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, and multiple sclerosis. Lung injury caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is largely the result of the promotion of inflammatory reactions by cytokines such as IL-17A. Dysregulation of IL-17 signaling promotes pathogenic inflammation. IL-17A has a pathogenic role in mediating the important inflammatory pathway of psoriasis. The IL-23/Th17/IL-17A pathway is a key link in its pathogenesis, and inhibiting the expression of IL-17A can effectively alleviate psoriasis ^[4]. IL-17A is also associated with the course of ankylosing spondylitis (AS), and IL-17A inhibitors can effectively treat AS ^[5]. In addition, studies have shown that IL-17A is involved in the pathogenesis of neurodegenerative diseases in the central nervous system, and its expression level is related to the severity and progression of the disease ^[3].

B6-hIL-17A mice are humanized mouse models that express human IL-17A protein. They were constructed by using gene editing technology to replace the sequence encoding the endogenous extracellular domain of the mouse Il17a gene with the corresponding sequence from the human IL17A gene while retaining the mouse signal peptide. This strain can be used for mechanism research and preclinical evaluation of therapeutic drugs for various chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, and multiple sclerosis. The homozygotes are viable and fertile.

Strain Strategy

The mouse Il17a endogenous extracellular domain (aa.26~158) was replaced with the human IL17A extracellular domain (aa.24~155). The murine signal peptide (aa.1~25) was kept.

Application

• Research on multiple chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, and multiple sclerosis;
• Preclinical evaluation of IL17A-neutralizing antibodies and small molecule inhibitors;
• More autoimmune disease research.

Validation Data

1. Experimental design

Figure 1. B6-hIL-17A mouse experimental timeline.

*Imiquimod (IMQ) induces psoriasis-like skin inflammation in mice ^[6].

*Ixekizumab is a humanized monoclonal antibody that reduces inflammation by binding to and neutralizing IL-17A for the treatment of certain autoimmune diseases such as psoriasis, psoriatic arthritis, ankylosing spondylitis, and non-radiographic axial spondyloarthritis ^[7].

2. Growth curve

Figure 2. Weight change curves of B6-hIL-17A mice and wild-type mice (B6N). The results show that the weight change trends of B6N and B6-hIL-17A mice are consistent, and mice can grow normally after IMQ treatment and Ixekizumab treatment.

3. Skin condition after IMQ induction

Figure 3. Skin status of 8-week-old female B6-hIL-17A mice and wild-type (WT) mice on the third day after IMQ induction. The results show that on the third day after IMQ induction, the skin of B6-hIL-17A mice showed obvious scales, and the scales in severe areas fell off in patches. Some areas showed erythema and the skin thickness was slightly larger than normal, and the skin surface was rough. Ixekizumab treatment can effectively improve the skin condition of B6-hIL-17A mice, and its therapeutic effect is dose-dependent, with a better effect in the high-dose treatment group.

4. Expression of human IL-17A protein

Figure 4. ELISA* results of human IL-17A protein in the serum of 8-week-old female B6-hIL-17A mice and wild-type mice (B6N). In the absence of IMQ treatment, B6-hIL-17A mice express trace amounts of human IL-17A protein, which can be detected by ELISA. IMQ treatment triggers the mouse immune response and activates Th17 cells, leading to a significant increase in IL-17A expression. ELISA results showed that IMQ treatment significantly increased human IL-17A protein expression in B6-hIL-17A mice, while B6N wild-type mice showed no expression of human IL-17A. In addition, treatment with Ixekizumab restored human IL-17A protein expression in B6-hIL-17A mice to the level before IMQ induction, suggesting that the antibody has therapeutic effects in B6-hIL-17A mice.

*The “Human IL-17A ELISA Kit” used for the detection is provided by MULTISCIENCES (stock number: EK117/2-96).

5. Psoriasis Area and Severity Index (PASI)*

Figure 5. PASI scores of 8-week-old female B6-hIL-17A mice and wild-type mice (B6N) after IMQ treatment and Ixekizumab treatment. The results show that B6-hIL-17A mice and B6N mice developed symptoms such as skin lesions, scales, erythema, and skin folds after IMQ application. After high-dose Ixekizumab treatment, the PASI scores of B6-hIL-17A mice significantly decreased to a level similar to that of wild-type mice, and skin symptoms were significantly reduced.

*Psoriasis Area and Severity Index (PASI): a tool that comprehensively evaluates the severity and range of psoriasis, including scoring for the area and severity of skin lesions; Erythema score: a rating of the degree of erythema on the skin surface; Scaling score: the degree of involvement based on the body surface area; Skin thickness score: an indicator used to evaluate the severity of skin symptoms in systemic sclerosis (SSc); Cumulative score: the total score.

6. Skin H&E staining

Figure 6. H&E staining, histological scoring, and skin surface thickness detection of 8-week-old female B6-hIL-17A mice and wild-type (WT&B6N) mice. The results showed that after IMQ was applied to the mice, excessive keratinization and incomplete keratinization appeared in the stratum corneum (red arrow); the granular layer in the epidermis became thinner or disappeared (green arrow); the spinous layer thickened (blue arrow); the dermal papilla extended and undulated (yellow arrow); and single or multiple nuclear cells infiltrated in the dermis (orange arrow). After treatment with Ixekizumab, the symptoms of the mice improved significantly.

References

[1] Cua DJ, Tato CM. Innate IL-17-producing cells: the sentinels of the immune system. Nat Rev Immunol. 2010 Jul;10(7):479-89. doi: 10.1038/nri2800. Epub 2010 Jun 18. Erratum in: Nat Rev Immunol. 2010 Aug;10(8):611. Erratum in: Nat Rev Immunol. 2010 Jul;10(7):following 489.
[2] Naik S, Bouladoux N, Linehan JL, Han SJ, Harrison OJ, Wilhelm C, Conlan S, Himmelfarb S, Byrd AL, Deming C, Quinones M, Brenchley JM, Kong HH, Tussiwand R, Murphy KM, Merad M, Segre JA, Belkaid Y. Commensal-dendritic-cell interaction specifies a unique protective skin immune signature. Nature. 2015 Apr 2;520(7545):104-8.
[3] Chen J, Liu X, Zhong Y. Interleukin-17A: The Key Cytokine in Neurodegenerative Diseases. Front Aging Neurosci. 2020 Sep 29;12:566922.
[4] Chiricozzi A, Krueger JG. IL-17 targeted therapies for psoriasis. Expert Opin Investig Drugs. 2013 Aug;22(8):993-1005.
[5] Baeten D, Sieper J, Braun J, Baraliakos X, Dougados M, Emery P, Deodhar A, Porter B, Martin R, Andersson M, Mpofu S, Richards HB; MEASURE 1 Study Group; MEASURE 2 Study Group. Secukinumab, an Interleukin-17A Inhibitor, in Ankylosing Spondylitis. N Engl J Med. 2015 Dec 24;373(26):2534-48.
[6] Christensen PKF, Hansen AK, Skov S, Martel BC, Larsen J, Høyer-Hansen MH, Koch J. Imiquimod induces skin inflammation in humanized BRGSF mice with limited human immune cell activity. PLoS One. 2023 Feb 17;18(2):e0281005.
[7] Versus Arthritis. (2023, December 21). Ixekizumab. Versus Arthritis. https://www.versusarthritis.org/about-arthritis/treatments/drugs/ixekizumab/