Background

It is well known that immunogenicity evaluation is a pivotal aspect of therapeutic protein drug development. These drugs, such as antibody drugs, may be recognized and cleared by the immune system upon administration. To mitigate this risk, researchers must assess immunogenicity and potentially modify the drugs to avoid immune responses.

Animal experiments serve as valuable tools in this evaluation process, offering control over variables such as dosage and administration methods. Through animal studies, researchers can simulate human reactions, enhancing safety for clinical trial volunteers. Additionally, the shorter duration of animal testing allows for efficient resource utilization and rapid adjustments based on results.

How to Conduct Immunogenicity Assessment Animal Experiments

So, how do you verify the immunogenicity of therapeutic antibody drugs in animal models?

First of all, selecting appropriate animal models is vital, with HLA-transgenic mice or fully humanized mice being preferred due to their expression of key human immune recognition molecules. These models facilitate the simulation of immunogenicity.

Then, therapeutic proteins are injected into animals to imitate immunoreaction in human beings. Researchers detect the changes in weight, behavior, and physiological parameters to discern any adverse reactions. Blood samples are obtained for laboratory analysis, wherein tests like ELISA are employed to detect antibodies produced by the animal's immune system against the administered drugs, commonly referred to as anti-drug antibodies (ADA). These antibodies serve as key indicators for assessing immunogenicity.

Following the administration of antibody drugs, the absence of noticeable adverse reactions in animals and non-detection of anti-drug antibodies in serum samples, tentatively means low immunogenicity.

Last but not least, similar research endeavors delve into whether such antibody drugs impact immune system functionality. Parameters such as alterations in immune cell counts or compromised capabilities to combat other pathogens are meticulously examined.

Through these studies, researchers can comprehensively evaluate the immunogenicity of antibody drugs.

HLA Transgenic Mice Introduction

HLA transgenic mice, which contain human HLA genes, are a type of genetically engineered mice widely used in various immunological studies, especially in developing potent vaccines and immunotherapies.

By replacing the native MHC molecules with human HLA genes, these mice effectively mimic human immune responses, offering scientists an unparalleled window into understanding how the human immune system responds to specific pathogens and diseases.

Additionally, the pivotal role of HLA transgenic mice extends into drug development research. If a drug exhibits positive effects in this model organism, it may also generate similar results in humans. Conversely, severe side effects witnessed in these animal models signals potential unsuitability for human use.

In conclusion, HLA transgenic mice represent an invaluable asset for researchers, enabling them to simulate human immune responses effectively, thus propelling advancements in immunology and drug development research.

• What Are HLA Class II Transgenic Mouse Models

HLA Class II transgenic mouse models can be classified into several types by the expression of different HLA molecules:

HLA-DR transgenic mice: This model expresses the HLA-DR molecule, which is mainly found on antigen-presenting cells such as dendritic cells and B lymphocytes, and is involved in CD4⁺ T cell-mediated immune responses.

Fig. 1 HLA molecules in transgenic mice lacking endogenous class II molecules can shape the T cell repertoire in the thymus of mice.¹

HLA-DQ transgenic mice: This model expresses the HLA-DQ molecule, which is also found on the surface of antigen-presenting cells. However, in certain human diseases like type 1 diabetes, the role of DQ molecules seems more prominent.

HLA-DP transgenic mice: This model expresses the HLA-DP molecule, relatively rare in the human body, is generally only detected in specific specific antigen presenting cells.

These models serve as invaluable tools for analyzing CD4⁺ T cell responses elicited by antibody drugs and assessing their immunogenicity of the antibody drug.

Completely Humanized Mice Model

Humanized mice, as their name suggests, are mice that have been genetically modified to carry human genes or tissues, thus making them more relevant models to study human diseases and responses. By introducing human-specific genes or cells, these rodents can closely mimic human biological responses, enhancing the relevance of research findings.

The replacement of MHC molecules with the human leukocyte antigen (HLA) gene creates a HLA-transgenic mouse model, facilitating a more faithful simulation of human immune responses. This breakthrough paves the way for deeper insights into how the human body reacts to diverse diseases and pathogens.

Moreover, these HLA-transgenic mice hold pivotal significance in drug development research and therapeutic design. Positive outcomes observed with drugs in these models herald promising efficacy in humans, while adverse effects serve as red flags, signaling potential unsuitability for human use.

In conclusion, HLA-transgenic mice provide scientists with a tool that propels the frontiers of immunology and drug development, offering a more accurate representation of human immune responses.

Comparison Between HLA Class II Transgenic Mice Model and Completely Humanized Mice Model

HLA transgenic mice are genetically modified rodents wherein one or more human HLA genes are introduced into a non-human background, facilitating the expression of human HLA molecules. This model enables researchers to observe the specific functions of these HLA molecules, particularly in antibody responses, including autoimmune diseases, within an in vivo context.

Humanized mice, on the other hand, refer to the comprehensive construction of the human immune system in mice, thus simulating human immune responses. This is achieved through various techniques such as gene modification or hematopoietic stem cell transplantation, resulting in a predominantly or entirely humanized immune cell population within the mouse.

The differences between these models mainly hinge on two points:

Humanization and level of detail: HLA transgenic mice undergo humanization at a specific gene level, while humanized mice undergo comprehensive humanization at the entire immune system level.

Range of applicable research: HLA transgenic mice are primarily used for investigating the roles of HLA genes or molecules in immune responses, whereas humanized mice can be used for a broader range of immune response research, including the interaction of immune cells and the comprehensive regulation of immune responses.

Application in Immunogenicity Assessment of Therapeutic Proteins

Many therapeutic proteins are engineered to escape human immune surveillance. For example, lysozyme used this strategy to treat Staphylococcus aureus infections, and it was named F12^[2]. Lysozyme specifically kills Staphylococcus aureus by hydrolyzing cell wall peptidoglycan. However, treatment with staphylococcin has the potential to cause anti-drug antibodies (ADAs) in human subjects.

To address this, researchers employ techniques such as deleting the T cell epitope of lysozyme F12 to reduce its immunogenicity. In vivo experiments utilize two HLA transgenic mouse models, wherein endogenous mouse MHC II is replaced with human MHC II alleles DRB1*0401 (DR4) or DRB1*1501 (DR2). These alleles represent the "DR4" and "major DR" human MHC II supertypes, respectively. The study demonstrates that in both HLA transgenic mouse models, the elimination of human MHC II-restricted T cell epitopes in lysozyme F12 results in a significant reduction in in vivo immunogenicity.

Creative Biolabs

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All listed services and products are For Research Use Only. Do Not use in any diagnostic or therapeutic applications.