investigating-target-gene-function-cd40-agonistic-antibody-induced

Investigating Target Gene Function in a CD40 Agonistic Antibody-induced Colitis Model using CRISPR/Cas9-based Technologies

The immune system functions to defend humans against foreign invaders such as bacteria and viruses. However, disorders of the immune system may lead to ...

AbbVie, Cambridge Research Center

Inflammatory bowel diseases (IBD) are complex, multifactorial disorders characterized by chronic relapsing intestinal inflammation. IBD is diagnosed around 1 in 1000 individuals in Western countries with globally increasing incident rates. Association studies have identified hundreds of genes that are linked to IBD and potentially regulate its pathology. The further dissection of the genetic network underlining IBD pathogenesis and pathophysiology is hindered by the limited capacity to functionally characterize each genetic association, including generating knockout animal models for every associated gene. Cutting-edge CRISPR/Cas9-based technology may transform the field of IBD research by efficiently and effectively introducing genetic alterations. In the present study, we used CRISPR/Cas9-based technologies to genetically modify hematopoietic stem cells. Through cell sorting and bone marrow transplantation, we established a system to knock out target gene expression by over 90% in the immune system of reconstituted animals. Using a CD40-mediated colitis model, we further validated our CRISPR/Cas9-based platform for investigating gene function in experimental IBD. In doing so, we developed a model system that delivers genetically modified mice in a manner much faster than conventional methodology, significantly reducing the time from target identification to in vivo target validation and expediting drug development.

CRISPR/Cas9-targeting of CD40 in hematopoietic stem cells limits immune activation mediated by anti-CD40.

CRISPR/Cas9-based genome editing has been widely used to evaluate target gene function in biomedical research. The CRISPR/Cas9 system can introduce gene knockout, knock-in and mutations with more ease than earlier generations of genome editing tools. Using CRISPR/Cas9-based genome editing, researchers have successfully modified the DNA of different immune components, including primary T cells, B cells, macrophages, and immune system progenitors, i.e. hematopoietic stem cells (HSCs), which are also known as Lin-Sca1 + Kit + cells (LSKs) in mice. We previously reported that the transplantation of HSCs with lentivirus-mediated CRISPR/Cas9-based genetic modifications into lethally irradiated congenic mice repopulated the ablated recipient immune system with the donor immune system. In this report, we efficiently manipulated CD40 expression in LSK cells using Cas9 RNP and demonstrated the functional impact in a colitis model. Compared to a virus-based strategy, the RNP approach has the potential to enable investigation of target gene biology in any mouse strain and eliminates the time and effort associated with virus production and infection. Therefore, in vivo RNP-based CRISPR/Cas9 gene editing of transplanted HSCs represents a promising new strategy for exploring gene function in the immune system of mice.

Article	Year
CRISPR/Cas9-targeting of CD40 in hematopoietic stem cells limits immune activation mediated by anti-CD40. PloS one\| PubMed ID: 32155151	2020
Editing the immune system in vivo in mice using CRISPR/Cas9 ribonucleoprotein (RNP)-mediated gene editing of transplanted hematopoietic stem cells. Methods (San Diego, Calif.)\| PubMed ID: 33422676	2021

Sean Graham

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