IL 17 Mouse

What is IL-17A and how does its structure and function compare between mice and humans?

Mouse IL-17A is a 21 kDa variably glycosylated polypeptide belonging to the IL-17 family of cytokines containing a cysteine-knot fold. It is synthesized as a 158 amino acid precursor that contains a 25 amino acid signal sequence and a 15 kDa, 133 amino acid mature segment . Mature mouse IL-17A shares 61% amino acid identity with human IL-17A and 89% with rat IL-17A . Despite this moderate sequence identity, human IL-17 is functionally active on mouse cells, an important consideration for translational studies .

In both species, IL-17A forms either a 35-38 kDa homodimer or a 45-48 kDa heterodimer with IL-17F . Both mouse and human IL-17A contain one conserved N-linked glycosylation site that contributes approximately 5 kDa to the native molecular weight . Functionally, IL-17A serves as a pro-inflammatory cytokine in both mice and humans, playing key roles in mucosal immunity .

Which cells produce IL-17 in mice and how does this compare to humans?

In mice, several immune cell populations have been identified as sources of IL-17:

• CD4+ Th17 T cells

• Paneth cells

• GR1+CD11b+ myeloid suppressor cells

• CD27-gamma δ T cells

• CD1+NK1.1- iNKT cells

• CD3-CD4+ LTi-like cells

In mouse models, γδ T cells are particularly important IL-17 producers and indispensable for IL-17-mediated antifungal immunity in the oral mucosa . These cells represent a rapid source of IL-17 during early immune responses. The cell types producing IL-17 can vary depending on the tissue site and nature of the immune challenge, which is an important consideration when designing mouse experiments .

What are standardized methods for measuring IL-17 in mouse samples?

Quantitative measurement of mouse IL-17 typically employs ELISA techniques. The Quantikine Mouse IL-17 Immunoassay is a solid-phase ELISA designed specifically for measuring mouse IL-17 in cell culture supernatants, serum, and plasma samples . This assay utilizes E. coli-expressed recombinant mouse IL-17 and antibodies raised against this recombinant factor .

When measuring IL-17 in mouse samples, researchers should be aware of the following performance metrics:

This data indicates high precision and accuracy across various sample types . Alternative methods include flow cytometry for intracellular staining, qPCR for mRNA expression, and multiplex assays when measuring multiple cytokines simultaneously.

What are the essential mouse models used in IL-17 research?

Several mouse models are crucial for IL-17 research:

• IL-17A knockout mice: These mice demonstrate increased susceptibility to cutaneous infection with Candida albicans .

• IL-17RA knockout mice: These mice show larger skin lesions with higher bacterial counts upon cutaneous Staphylococcus aureus infection .

• IL-17A/F double knockout mice: These mice are particularly susceptible to S. aureus infection, developing mucocutaneous abscesses around the nose and mouth .

• Conditional knockout models: These allow tissue-specific deletion of IL-17 signaling components. For example, mice with IL-17Ra deficiency specifically in S1DZ neurons show altered social behaviors .

• Experimental autoimmune encephalomyelitis (EAE): This model mimics human multiple sclerosis and is used to study IL-17's role in CNS inflammation. EAE mice lacking IL-17 show resistance to MS-like symptoms .

When selecting a model, researchers should consider the specific aspect of IL-17 biology they wish to investigate, as different models reveal distinct functions of the IL-17 pathway.

How does IL-17 mediate mucocutaneous immunity against pathogens in mice?

IL-17A and IL-17F play crucial roles in mucocutaneous protection against pathogens in mice, particularly against Candida albicans and Staphylococcus aureus. The protective mechanisms involve several coordinated processes:

In the case of C. albicans, IL-17A-deficient mice show increased susceptibility to cutaneous infection . The IL-23/IL-17 axis is particularly important, as mice lacking IL-12p40 or IL-23p19 (subunits of IL-23, which is essential for TH17 cell development) also display high fungal burdens in the skin when challenged with C. albicans . This suggests that IL-17 mediates antifungal immunity through recruitment and activation of neutrophils and expression of antimicrobial peptides at epithelial surfaces.

For S. aureus defense, IL-17RA- and γδ T cell-deficient mice develop larger skin lesions with higher bacterial counts upon cutaneous infection . Importantly, administration of recombinant IL-17A can rescue this phenotype in γδ T cell-deficient mice, confirming the direct protective role of this cytokine . Mice lacking both IL-17A and IL-17F show even greater susceptibility, developing mucocutaneous abscesses around the nose and mouth .

These findings highlight that while IL-17 is often associated with pathological inflammation, its primary evolutionary role appears to be in host defense against specific mucocutaneous pathogens.

What role does IL-17 play in neurological function and sociability in mouse models?

Recent research has revealed unexpected roles for IL-17 in neurological function, particularly related to social behavior. IL-17 receptor subunit a (IL-17Ra) is expressed in cortical neurons, including in the somatosensory cortex dysgranular zone (S1DZ) . This expression pattern enables direct neuronal responses to IL-17a.

The relationship between inflammation and social behavior is complex. While prenatal exposure to IL-17a can contribute to neurodevelopmental disorders, acute IL-17a exposure in adult MIA offspring can paradoxically ameliorate sociability deficits . This effect appears specific to individuals with prenatal immune activation, as LPS treatment increases IL-17a levels in the blood selectively in MIA offspring but not in other monogenic mutant mice .

These findings suggest a novel neuroimmune mechanism by which IL-17a can directly modulate neural activity and behavior, expanding our understanding of cytokine functions beyond traditional immune roles.

How does IL-17 contribute to pathogenesis in mouse models of multiple sclerosis?

In experimental autoimmune encephalomyelitis (EAE), the mouse model of multiple sclerosis, IL-17A plays a critical role in promoting inflammation in the central nervous system. EAE mice lacking IL-17 demonstrate remarkable resistance to MS-like symptoms . While all standard EAE mice develop severe symptoms within 20 days after encephalomyelitis induction, only 35% of IL-17-deficient EAE mice show clinical signs, and these are mild in severity .

The mechanism involves several coordinated steps:

• IL-17A promotes recruitment of inflammatory cells to the CNS

• IL-17A-deficient EAE mice have significantly fewer immune cells (particularly CD4+ and gamma delta T-cells) in the spinal cord

• Absence of IL-17 correlates with reduced levels of IL-1-beta

• IL-17A mobilizes neutrophils and inflammatory monocytes that secrete IL-1-beta to lymph nodes

These findings align with clinical observations in human MS, where Th17 cells are implicated in disease pathogenesis. Early clinical trials with secukinumab (an IL-17 neutralizing antibody) in relapsing-remitting MS have shown promising results , suggesting translational relevance of the mouse model findings.

What methodological approaches can resolve contradictory data in IL-17 mouse studies?

Contradictory findings in IL-17 research often stem from differences in experimental design. To resolve such contradictions, researchers should consider:

• Strain-specific effects: The genetic background of mice can significantly influence IL-17 biology. C57BL/6, BALB/c, and other common strains may show different phenotypes. Always report the complete genetic background of experimental animals.

• Microbiome influences: The gut microbiota significantly affects IL-17 responses. Standardizing housing conditions, diet, and considering co-housing of experimental groups can control for this variable .

• Temporal dynamics: The timing of IL-17 action can determine its effects. For instance, IL-17a exposure during embryonic development versus adulthood can produce opposite behavioral outcomes . Time-course experiments are essential.

• Contextual factors: IL-17 may have different effects depending on the inflammatory context. For example, IL-17 promotes sociability in MIA offspring after LPS treatment but not in monogenic mutant mice without prenatal immune activation .

• Dose-dependent effects: IL-17 may have different, even opposing effects at low versus high concentrations. Dose-response studies are crucial.

• Cell-specific responses: Conditional knockout models that delete IL-17 signaling components in specific cell types can resolve contradictions arising from global deletion studies .

Implementing these methodological considerations can help reconcile apparently contradictory findings and advance our understanding of IL-17 biology.

How do IL-17A and IL-17F interact in mouse immune responses, and what are the phenotypic differences between single and double knockout models?

IL-17A and IL-17F can function both independently and cooperatively in mouse immune responses. Mouse IL-17A forms both a 35-38 kDa homodimer and a 45-48 kDa heterodimer with IL-17F . These different configurations may activate slightly different downstream signaling pathways.

The phenotypic differences between knockout models reveal distinct and overlapping functions:

• IL-17A knockout mice: Show increased susceptibility to cutaneous C. albicans infection but retain some protection against S. aureus .

• IL-17F knockout mice: Generally display milder immunodeficiency compared to IL-17A knockouts.

• IL-17A/F double knockout mice: Demonstrate more severe susceptibility to S. aureus than either single knockout, developing distinctive mucocutaneous abscesses around the nose and mouth . This suggests a synergistic or redundant role for these cytokines.

• IL-17RA knockout mice: Show broader defects since IL-17RA is required for signaling by multiple IL-17 family members. These mice develop larger skin lesions with higher bacterial counts upon cutaneous S. aureus infection .

These comparative phenotypes suggest that while IL-17A and IL-17F have some redundant functions, they also play distinct roles in protective immunity. The more severe phenotype in double knockout models highlights the importance of studying cytokine families as functional networks rather than isolated factors.

What are the latest advances in targeting IL-17 in mouse models that could translate to human therapeutics?

Recent research in mouse models has revealed several promising therapeutic approaches targeting IL-17:

• Neurological disorders: The discovery that IL-17a can ameliorate social behavior deficits in certain contexts suggests potential for targeted IL-17 modulation in specific patient subsets with neurodevelopmental disorders . Mouse studies suggest that patients whose behavioral symptoms improve during inflammation might benefit from IL-17-targeted approaches.

• Multiple sclerosis: EAE mouse studies strongly support IL-17 neutralization as a therapeutic strategy. The effectiveness of secukinumab in early MS trials validates this translational approach . Mouse models suggest that targeting IL-17 may be most effective in certain inflammatory subtypes of MS.

• Mucosal infections: Understanding IL-17's protective role against C. albicans and S. aureus in mice has raised important considerations for IL-17 inhibitor therapy in humans . The increased risk of mucocutaneous infections observed in patients receiving IL-17 inhibitors for psoriasis was predictable from mouse models.

• Tissue-specific targeting: Mouse studies with conditional IL-17Ra deletion suggest that tissue-specific targeting might provide therapeutic benefits while minimizing adverse effects . This approach could revolutionize IL-17-targeted therapy.

The translation from mouse to human medicine requires careful consideration of species differences in IL-17 biology, but mouse models continue to provide valuable insights that inform clinical development.

What are the optimal protocols for generating IL-17-producing cells from mouse tissues?

To generate and study IL-17-producing cells from mouse tissues, researchers can follow these methodological approaches:

• Th17 cell generation:

  • Isolate naïve CD4+ T cells from mouse spleen and lymph nodes using negative selection

  • Culture cells with plate-bound anti-CD3 (2-5 μg/ml) and soluble anti-CD28 (2 μg/ml)

  • Add cytokine cocktail: TGF-β (2-5 ng/ml), IL-6 (20-30 ng/ml), IL-23 (20 ng/ml)

  • Include neutralizing antibodies against IFN-γ and IL-4 to prevent Th1/Th2 differentiation

  • Culture for 3-5 days before assessment

• γδ T cell isolation and stimulation:

  • γδ T cells are major producers of IL-17 in mice, particularly in mucosal tissues

  • Isolate cells from lymphoid organs or epithelial tissues using magnetic or flow cytometric separation

  • Stimulate with IL-1β + IL-23 for optimal IL-17 production without TCR engagement

  • Alternative stimulation: PMA/ionomycin for 4-6 hours with Brefeldin A added for intracellular cytokine staining

• Innate lymphoid cells:

  • Isolate cells from mucosal tissues (intestine, lung) using enzymatic digestion

  • Enrich for lineage-negative cells by depleting cells expressing common lineage markers

  • Stimulate with IL-1β + IL-23 for 24-48 hours

• Ex vivo restimulation protocol:

  • For cells isolated from immunized or infected mice

  • Restimulate with PMA (50 ng/ml) and ionomycin (750 ng/ml) for 4-6 hours

  • Add protein transport inhibitors (Brefeldin A or Monensin) for the final 2-4 hours

  • Perform intracellular cytokine staining for IL-17A and IL-17F

These protocols should be optimized for specific mouse strains and experimental contexts.

How should researchers interpret differences between IL-17 levels in mouse versus human systems?

When comparing IL-17 levels between mouse and human systems, researchers should consider several key factors:

• Baseline differences: Mouse tissues often show different constitutive expression of IL-17 compared to equivalent human tissues. Murine skin and mucosal tissues typically show higher baseline IL-17 signaling due to their commensal microbiota .

• Cellular sources: While both species produce IL-17 from Th17 cells, mice have a greater proportion of IL-17 coming from γδ T cells, particularly at mucosal surfaces . In humans, conventional Th17 cells and MAIT cells may contribute proportionally more.

• Commensal status: C. albicans is a commensal in humans but not in mice, while S. aureus is commensal in mice . These differences affect baseline IL-17 levels and responses.

• Quantitative comparisons: When measuring IL-17, species-specific assays must be used. Mouse IL-17A and human IL-17A show only 61% amino acid identity , necessitating different detection antibodies.

• Functional conservation: Despite sequence differences, human IL-17 is active on mouse cells . This cross-reactivity allows for certain types of translational experiments.

• Disease relevance: In some pathologies like psoriasis, the IL-17 pathway appears similarly dysregulated in both species, while in others (like certain neurological conditions), there may be species-specific differences .

Researchers should avoid direct numerical comparisons between mouse and human IL-17 levels and instead focus on relative changes in response to stimuli or disease states.

What experimental design elements are critical for studying IL-17 function in neuroinflammatory mouse models?

When designing experiments to study IL-17 function in neuroinflammatory models such as EAE, researchers should incorporate these critical elements:

• Timing considerations:

  • The same cytokine can have opposing effects depending on developmental timing. For example, IL-17a causes behavioral deficits during embryonic development but can ameliorate them in adults

  • Include time-course experiments with cytokine measurements at multiple points

  • Consider both acute and chronic effects of IL-17 modulation

• Regional specificity:

  • IL-17 receptors show regional distribution in the brain

  • Use stereotactic injection techniques for targeted delivery to specific brain regions

  • Employ conditional knockout models with region-specific Cre drivers

• Behavioral assessment:

  • Include a battery of behavioral tests to assess multiple domains

  • For social behavior studies, use three-chamber sociability tests

  • Include cognitive assessments (Morris water maze, novel object recognition)

  • Assess motor function as a control for non-specific effects

• Electrophysiological measurements:

  • Multi-electrode arrays can measure firing rates in specific brain regions in awake animals

  • Compare baseline vs. post-treatment neural activity

  • Correlate electrophysiological changes with behavioral outcomes

• Control groups:

  • Include both wild-type and vehicle-treated controls

  • For maternal immune activation models, include offspring from both poly(I:C) and saline-treated mothers

  • Consider including positive control groups (e.g., known anti-inflammatory treatments)

• Mechanistic validation:

  • Use blocking antibodies against IL-17a via intracerebroventricular injection

  • Employ recombinant IL-17a at physiologically relevant concentrations

  • Include rescue experiments to confirm causal relationships

These design elements help establish causal relationships between IL-17 signaling and neuroinflammatory phenotypes while controlling for confounding variables.

How can researchers integrate IL-17 mouse data with human clinical findings to advance translational research?

Effective integration of mouse IL-17 data with human clinical findings requires thoughtful analytical approaches:

• Cross-species pathway analysis:

  • Focus on conserved signaling pathways rather than absolute cytokine levels

  • Identify shared transcriptional signatures downstream of IL-17 signaling across species

  • Use bioinformatic tools to compare mouse and human IL-17-responsive gene networks

• Translational biomarkers:

  • Identify biomarkers of IL-17 activity that are valid in both species

  • Measure parallel changes in these biomarkers in mouse models and human patients

  • Examples include antimicrobial peptides, neutrophil-recruiting chemokines, and epidermal hyperplasia markers

• Predictive validity assessment:

  • Test whether interventions that modulate IL-17 in mice produce proportional effects in humans

  • Compare dose-response relationships between species

  • Develop mathematical models to predict human responses from mouse data

• Stratification approaches:

  • Identify patient subgroups that may respond similarly to mouse models

  • For example, patients with neurodevelopmental disorders whose symptoms improve during inflammation might respond to IL-17 modulation similarly to MIA mice

• Reverse translation:

  • Design mouse experiments based on human genetic findings (e.g., IL-17 pathway variants)

  • Create humanized mouse models expressing human IL-17 pathway components

  • Use CRISPR to introduce human disease-associated IL-17 pathway variants into mice

• Integrated analysis frameworks:

  • Develop computational models that incorporate both mouse and human data

  • Use Bayesian approaches that update predictions as new data becomes available

  • Apply machine learning to identify patterns across species that might not be apparent in conventional analyses

This integrative approach can accelerate translation of mouse findings to human applications while acknowledging the limitations of cross-species comparisons.

What statistical approaches are most appropriate for analyzing complex IL-17 dataset from mouse experiments?

When analyzing complex IL-17 datasets from mouse experiments, researchers should consider these statistical approaches:

• For longitudinal data:

  • Mixed-effects models account for both fixed effects (treatment, genotype) and random effects (individual mouse variation)

  • Repeated measures ANOVA with appropriate post-hoc tests for time-course experiments

  • Area under the curve (AUC) analysis to capture cumulative effects over time

• For multivariate cytokine data:

  • Principal component analysis (PCA) to identify patterns in complex cytokine networks

  • Hierarchical clustering to identify groups of co-regulated cytokines

  • Partial least squares discriminant analysis (PLS-DA) to identify cytokine signatures that distinguish experimental groups

• For dose-response relationships:

  • Non-linear regression with appropriate models (sigmoidal, bell-shaped)

  • EC50/IC50 calculations for potency comparisons

  • Bootstrapping methods to generate confidence intervals for potency parameters

• For transcriptomic/proteomic data:

  • Pathway enrichment analysis to identify IL-17-regulated biological processes

  • Gene set enrichment analysis (GSEA) to detect subtle but coordinated changes

  • Network analysis to identify hub genes in IL-17 signaling networks

• For behavioral data correlated with IL-17 levels:

  • Multiple regression models to account for confounding variables

  • Mediation analysis to test whether IL-17 effects on behavior are direct or indirect

  • Structural equation modeling for complex causal relationships

• For experimental design considerations:

  • Power analysis to determine appropriate sample sizes (typically 8-12 mice per group for most IL-17 studies)

  • Bootstrapping or permutation tests for non-normally distributed data

  • Multiple comparison correction (e.g., Benjamini-Hochberg) for high-dimensional datasets

These approaches help extract meaningful biological insights from complex experimental data while controlling for the multiple sources of variation inherent in mouse studies.

What are emerging areas for IL-17 research in mouse models beyond traditional immunology?

Several exciting frontier areas for IL-17 research in mouse models extend beyond traditional immunology:

• Neuroimmunology and behavior:

  • Further exploration of IL-17's direct effects on neuronal function and behavior

  • Investigation of IL-17's role in neurodevelopmental disorders, neurodegeneration, and neuropsychiatric conditions

  • Examination of region-specific effects in different brain areas

• Metabolic regulation:

  • IL-17's effects on adipose tissue inflammation and insulin resistance

  • Interactions between IL-17 and the gut microbiome in metabolic disorders

  • IL-17's role in regulating energy expenditure and thermogenesis

• Tissue regeneration and repair:

  • IL-17's dual roles in tissue damage and repair processes

  • The function of IL-17 in stem cell biology and tissue regeneration

  • IL-17 signaling in wound healing and epithelial barrier restoration

• Aging biology:

  • Age-related changes in IL-17 production and responsiveness

  • IL-17's contribution to inflammaging processes

  • Potential interventions targeting the IL-17 pathway to promote healthy aging

• Tumor immunobiology:

  • Context-dependent pro- and anti-tumorigenic roles of IL-17

  • IL-17's effects on the tumor microenvironment and immunotherapy responses

  • Combination approaches targeting IL-17 alongside checkpoint inhibitors

• Circadian regulation:

  • Circadian rhythms in IL-17 production and signaling

  • IL-17's role in mediating interactions between the immune system and circadian clocks

  • Chronotherapeutic approaches to IL-17-targeted interventions

These emerging areas highlight the increasingly recognized roles of IL-17 beyond classical inflammation, suggesting its fundamental importance in diverse physiological and pathological processes.

How might single-cell technologies advance our understanding of IL-17 biology in mouse models?

Single-cell technologies offer unprecedented opportunities to advance IL-17 research in mouse models:

• Single-cell RNA sequencing (scRNA-seq):

  • Identification of novel IL-17-producing cell populations

  • Characterization of heterogeneous responses to IL-17 across different cell types

  • Mapping of IL-17 receptor expression at single-cell resolution across tissues

  • Trajectory analysis to understand the development and plasticity of IL-17-producing cells

• Spatial transcriptomics:

  • Visualization of IL-17 signaling networks in their native tissue architecture

  • Mapping of spatial relationships between IL-17-producing and IL-17-responsive cells

  • Identification of tissue microniches with unique IL-17 signaling characteristics

• CyTOF/spectral flow cytometry:

  • High-dimensional phenotyping of IL-17-producing cells

  • Simultaneous assessment of multiple cytokines alongside IL-17

  • Identification of rare IL-17-producing populations in complex tissues

• Single-cell ATAC-seq:

  • Characterization of chromatin accessibility changes in response to IL-17

  • Identification of transcription factor binding motifs in IL-17-responsive genes

  • Mapping of epigenetic landscapes in IL-17-producing cells

• Single-cell multi-omics:

  • Integrated analysis of transcriptome, proteome, and epigenome in IL-17 biology

  • Correlation of cellular states with IL-17 production and responsiveness

  • Identification of regulatory networks controlling IL-17 expression

• Lineage tracing combined with single-cell technologies:

  • Tracking the fate of IL-17-producing cells during development and disease

  • Understanding the plasticity and stability of the IL-17-producing phenotype

  • Identifying precursor-product relationships in IL-17-producing cell lineages