Inflammatory Bowel Disease (IBD) Mouse Models

• Dextran Sodium Sulfate (DSS) Induction: DSS is a commonly used chemical that disrupts the intestinal epithelial barrier, leading to acute colitis. Mice are given DSS in their drinking water for a set period, followed by a recovery phase. This model is widely used to study acute inflammation, intestinal damage, and immune response. DSS can be dosed both acutely and chronically, leading to different disease progression timelines.
• T Cell Transfer Model: In this method, CD4+ T cells are isolated from a donor mouse and transferred into a recipient mouse, which induces chronic colitis. This model mimics the autoimmune aspect of IBD, as it is driven by T-cell-mediated inflammation. It is particularly useful for studying T-cell interactions and immunotherapy.
• Genetically Modified Mice: Some genetically modified mice, such as IL-10 knockout mice, spontaneously develop chronic colitis resembling human IBD. These mice have impaired immune regulation, making them valuable for long-term studies of immune tolerance and chronic inflammation.
• Trinitrobenzenesulfonic Acid (TNBS) Induction: TNBS is used to induce colitis by chemically modifying proteins in the colon and triggering an immune response. This model is more commonly used for studying Th1-driven inflammation and tissue damage in the intestines.

• Longitudinal Sectioning: Longitudinal sections of the colon allow for a more comprehensive view of the intestinal tissue. By preparing longitudinal sections, we can assess the entire colon, reducing variability that can occur when only part of the colon is sampled. This approach also ensures better representation of colonic inflammation and lesion distribution.
• Histopathological Scoring: After sectioning, histopathological analysis is conducted by our in-house veterinary pathologists to evaluate inflammatory cell infiltration, tissue damage, and the presence of ulceration. Standardized scoring systems (e.g., the Histological Disease Activity Index) can be additionally used to assess the severity and extent of inflammation consistently across samples, minimizing observer bias.

Download our IBD mouse model leaflet to view example histopathology analyses in the IBD mouse model.

In models like DSS-induced colitis, strains such as C57BL/6 often show severe and acute inflammation, while BALB/c mice might exhibit milder disease and more chronic patterns of inflammation. Genetically modified strains (e.g., IL-10 knockout mice) typically develop chronic IBD due to impaired immune regulation, making them ideal for studying long-term disease progression. The mouse strain selection is crucial when designing studies as it affects immune responses, disease patterns, and the efficacy of therapeutic interventions.

Reach out to our study directors who will help you determine the most optimal mouse strain for your preclinical IBD studies.

Maintaining microbiome consistency is crucial for ensuring reliable and reproducible results in Inflammatory Bowel Disease (IBD) studies. At InnoSer we take several steps to ensure reliability and reproducibility of your results in IBD studies, such as:

• Cohousing Mice: In IBD studies, we cohouse mice to reduce differences in microbiome composition between individual animals. Cohousing allows for natural microbial transfer between animals, promoting a more consistent microbiome across groups. This helps mitigate variations that could arise from isolated housing and provides more uniform conditions for all mice in the study. Cohousing also enables us to divide mice within the same cage into different treatment groups. By doing so, we account for intercage differences in the microbiome and reduce potential confounding effects of the microbiome on the study outcomes. This approach ensures that treatment effects are less influenced by microbiome variability and are more representative of the treatment’s true impact.
• Standardizing Environmental Conditions: We also standardize housing conditions (e.g., food, bedding, and environmental controls) to reduce any extraneous factors that might alter the microbiome composition. By controlling for these environmental variables, we ensure more consistent microbiome profiles across study groups.

Reach out to our study directors to learn more about how we ensure consistency in results in our preclinical IBD studies.

The dropout rate in IBD studies is estimated to be around 10-15%, depending on factors such as study duration, DSS impact, and the strain and sex of the animals. This means that out of every 12 animals in a group, approximately 1-2 animals may be lost due to complications.

However, to ensure robust statistical power, we recommend planning for an additional ~20% extra animals to account for variability within groups. This approach helps maintain reliable study outcomes and minimizes the risk of insufficient data to draw conclusions.

Contact our scientific team to determine the optimal number of animals needed for your specific study design and ensure statistical significance.

In the IBD mouse model, standard readouts to assess efficacy comprise clinical observations and Disease Activity Index Score (DAI). Both are key markers of disease progression, allowing you to assess efficacy of your compounds longitudinally. Moreover, clinical signs and DAI are assessed daily to enable a robust assessment of efficacy. The DAI is the combined score of weight loss compared to initial weight, stool consistency, and bleeding.

Depending on your research goals, your compounds mechanism of action (MoA) and your study timelines (i.e., do you wish to perform initial proof-of-concept study or an in-depth confirmation of your compound’s MoA?), other readouts can be included:

• Intestinal Permeability & Proliferation (FITC-dextran & BrdU Assays): Helps you determine barrier integrity and evaluate epithelial cell regeneration, helping you understand how your test compound impacts gut permeability and repair.
• Histopathology & Immunohistochemistry (IHC): Helps you evaluate tissue inflammation. Histopathological activity index of the colon can be used to quantify structural damage and immune infiltration.
• Cytokine Profiling IL-1β, IL-6, TNF-α, Lipocalin-2) via multiplex MSD and/or ELISA: Provides you with key insights into local inflammatory responses within colon tissue, crucial for understanding how your test compound modulates the immune system.
• Immune cell profiling via flow cytometry: provides you with a detailed analysis of immune cell populations, enabling you to better understand the inflammatory response. At InnoSer, we offers both established flow cytometry immune cell panels and can alternatively also set-up customized panels on request.
• Myeloperoxidase (MPO) Activity Assay: Measures neutrophil infiltration as a marker of acute inflammation and immune activation in the colon.

Reach out to our expert study directors to inquire which readouts are the most suited to your current research goals.

Using appropriate positive controls is essential to validate the immune response in the IBD mouse model, assess the efficacy of your new therapeutic compounds and most importantly to benchmark the therapeutic profile of your compounds against existing treatments.

The choice of positive control depends on the hypothesis of the study – whether targeting inflammation, epithelial repair, or immune modulation. In Dextran Sodium Sulfate (DSS)-induced colitis models, a good positive control is a treatment known to reduce inflammation and mitigate colonic damage is 6-Thioguanine (Kverka et al., 2011). Another positive control that may be used in DSS mouse studies is cyclosporine; a calcineurin inhibitor, inhibits T cell activation and is widely used as an immunosuppressant, with its efficacy confirmed in patients with Ulcerative Colitis in several clinical trials (Weissman et al., 2019).

Reach out to our team to inquire about using appropriate positive and negative controls in the DSS mouse models.