IP 10 Mouse

What is IP-10 in mice and what are its alternative designations?

IP-10 (CXCL10) is a 10 kDa chemokine that belongs to the CXC chemokine superfamily. In mouse models, it is also known as cytokine responsive gene 2 (Crg-2) or mob-1. IP-10 is secreted from cells stimulated with type I and II interferons (IFNs) and lipopolysaccharide (LPS) . It is constitutively expressed at low levels in thymic, splenic, and lymph node stroma .

The mouse IP-10 gene (Cxcl10) has several aliases in scientific literature, including:

• C7

• CRG-2

• Crg2

• gIP-10

• Ifi10

• INP10

• IP10

• mob-1

• Scyb10

Understanding these alternative designations is essential when conducting literature searches, as different publications may use different nomenclature.

What is the molecular structure of mouse IP-10 and how does it differ from human IP-10?

Mouse IP-10 exhibits the typical chemokine structural fold consisting of:

• An extended N-terminal loop

• Three antiparallel β-strands

• A C-terminal helix lying obliquely across the β-sheet

The crystal structure of mouse IP-10 has been determined at 2.5 Å resolution, revealing a novel tetrameric association. In this tetramer, two conventional CXC chemokine dimers associate through their N-terminal regions to form a 12-stranded elongated β-sheet approximately 90 Å in length . This association differs significantly from previously studied tetramers of human IP-10.

Each molecule is stabilized by two disulfide bonds between conserved cysteines (positions 9:36 and 11:53) . The structure contains four molecules in the asymmetric unit, with all molecules having a similar core structure but differences in the N- and C-termini and loop regions.

Mouse IP-10 shares approximately 67% amino acid sequence identity with human IP-10 , indicating important structural differences that may affect receptor binding, oligomerization, and biological activity. These differences must be considered when extrapolating findings from mouse models to human applications.

What are the primary biological functions of IP-10 in mouse models?

Mouse IP-10 serves several critical functions in the immune system:

T Cell Recruitment and Activation

IP-10 functions as a chemoattractant for activated T cells, particularly Th1 lymphocytes, through interactions with the G-protein-coupled receptor CXCR3 . IP-10-deficient mice show impaired T cell responses to alloantigen stimulation in mixed lymphocyte reaction (MLR) assays and reduced T cell recruitment .

Immune Cell Migration

IP-10 stimulates the migration of monocytes and natural killer cells to sites of inflammation while having no activity on neutrophils . This selective activity helps shape the cellular composition of inflammatory infiltrates.

Regulation of Immune Cell Development

IP-10 plays a role in regulating T-cell and bone marrow progenitor maturation , contributing to the development of effective immune responses.

Vascular and Tissue Effects

Beyond immune cell recruitment, mouse IP-10 exhibits:

• Potent angiostatic activity (inhibiting formation of new blood vessels)

• Antifibrotic properties in various tissues

• Modulation of adhesion molecule expression

These functions make IP-10 a critical mediator in various inflammatory and immune-mediated processes in mice, with implications for models of infection, autoimmunity, and cancer.

What methods are available for measuring mouse IP-10 in biological samples?

Several validated methods are available for detecting and quantifying mouse IP-10:

Enzyme-Linked Immunosorbent Assays (ELISAs)

Commercial sandwich ELISA kits offer sensitive detection of mouse IP-10 in serum, plasma, cell culture supernatants, and tissue homogenates . These assays typically have the following performance characteristics:

Recovery rates in different sample types:

Matched Antibody Pair Kits

These kits provide pre-matched antibody pairs, standards, sample diluent, and streptavidin-HRP to develop customized ELISAs . They allow researchers to optimize protocols for specific experimental needs.

Developer Kits

Some manufacturers offer comprehensive developer kits containing all components required for quantitative measurement of natural and/or recombinant mouse IP-10 in sandwich ELISA format .

Assay Principles

Most IP-10 detection methods employ a sandwich format where:

• A target-specific antibody is coated to microplate wells

• Samples, standards, or controls are added and bind to the immobilized (capture) antibody

• A second (detector) antibody is added to form a sandwich

• A substrate solution reacts with the enzyme-antibody-target complex to produce measurable signal

• Signal intensity is directly proportional to IP-10 concentration

When selecting a detection method, researchers should consider required sensitivity, sample type and volume, need for multiplexing, and experimental objectives.

How is IP-10 expression regulated in mouse models?

IP-10 expression in mice is regulated through several mechanisms:

Transcriptional Regulation

• Interferons: Both type I (IFN-α/β) and type II (IFN-γ) interferons potently induce IP-10 expression, as reflected in its name (Interferon-gamma induced protein 10)

• Bacterial components: Lipopolysaccharide (LPS) can trigger IP-10 expression, making it relevant in infection models

• Primary response gene: IP-10 is a highly inducible, primary response gene, suggesting rapid transcriptional activation

Tissue Distribution

IP-10 is constitutively expressed at low levels in thymic, splenic, and lymph node stroma , with expression increasing dramatically during inflammation or infection.

Receptor Interactions

IP-10 shares the CXCR3 receptor with another chemokine called Mig (CXCL9) , creating potential for coordinated regulation of lymphocyte trafficking through this shared receptor pathway.

Oligomerization Effects

The tetrameric structure of mouse IP-10 affects its biological activity and may represent a regulatory mechanism through which IP-10 function is modulated in vivo . Different oligomeric forms of IP-10 may exhibit different activities.

Understanding these regulatory mechanisms is essential for experimental design, as the timing, magnitude, and context of IP-10 expression will significantly impact research outcomes.

What phenotypes are observed in IP-10 knockout mice?

IP-10 knockout mice (IP-10−/−) demonstrate several important immunological abnormalities that reveal the non-redundant functions of this chemokine:

Impaired T Cell Responses

IP-10−/− mice show reduced T cell activation and functionality . This impairment manifests as:

• Reduced responses to alloantigen stimulation in mixed lymphocyte reaction (MLR) assays

• Diminished T cell recruitment to sites of inflammation or infection

• Altered kinetics of immune cell trafficking during inflammatory responses

Inflammatory Disease Modifications

The absence of IP-10 affects the development and progression of various inflammatory conditions, often resulting in:

• Altered cellular composition of inflammatory infiltrates

• Modified cytokine/chemokine networks at sites of inflammation

• Changed disease trajectories in models of autoimmunity, infection, and tissue injury

Receptor Signaling Compensation

Despite sharing the CXCR3 receptor with other chemokines like Mig (CXCL9), the phenotype of IP-10−/− mice indicates that these other ligands cannot fully compensate for IP-10 deficiency .

These phenotypic abnormalities demonstrate that IP-10 plays unique and essential roles in immune function. When using IP-10 knockout mice, researchers should consider genetic background effects, potential compensatory mechanisms, and context-dependent requirements for IP-10 in specific disease models.

How can researchers design experiments to study IP-10 in mouse models of inflammatory diseases?

Designing robust experiments to study IP-10 in inflammatory disease models requires careful consideration of multiple factors:

Model Selection

• Choose models relevant to IP-10's known functions (T cell recruitment, angiostasis)

• Consider both acute and chronic inflammation models, as IP-10 may play different roles in each

• Select appropriate control groups, including wild-type littermates for genetic models

Experimental Approaches

• Genetic approaches: IP-10 knockout mice, conditional knockouts, or CXCR3-deficient mice

• Pharmacological interventions: Neutralizing antibodies against IP-10 or CXCR3 antagonists

• Expression analysis: Monitoring IP-10 levels in different tissues and timepoints

• Cell-specific responses: Examining effects on specific lymphocyte populations

Timing Considerations

IP-10 is an early response gene , so experimental timelines should include:

• Early timepoints (6-48 hours) to capture peak expression in acute inflammation

• Multiple timepoints in chronic models to assess sustained expression patterns

• Intervention timing based on expression kinetics in the specific model

Sample Collection and Processing

• Collect multiple sample types (serum, relevant tissues, infiltrating cells)

• Preserve samples appropriately for intended analyses (protein extraction, RNA isolation, histology)

• Consider using flow cytometry to identify IP-10-producing and responding cells

Comprehensive Readouts

Beyond measuring IP-10 levels, assess:

• T cell recruitment and activation markers

• Expression of CXCR3 on relevant cell populations

• Other chemokines that may compensate for or interact with IP-10

• Disease-specific pathological and functional outcomes

Controls and Validation

• Include appropriate age and sex-matched controls

• Validate key findings with complementary approaches

• Consider measuring other CXCR3 ligands to assess potential compensatory mechanisms

By addressing these experimental design considerations, researchers can generate more rigorous and interpretable data on IP-10's role in inflammatory disease pathogenesis.

What is known about the oligomerization of mouse IP-10 and its functional implications?

The oligomerization of mouse IP-10 has significant implications for its biological activity:

Structural Basis of Oligomerization

The crystal structure of mouse IP-10 reveals a novel tetrameric association where two conventional CXC chemokine dimers associate through their N-terminal regions to form a 12-stranded elongated β-sheet approximately 90 Å in length .

Functional Implications

Oligomerization affects multiple aspects of IP-10 biology:

• Receptor binding kinetics and signaling

• Glycosaminoglycan (GAG) interactions, which influence gradient formation

• In vivo stability and half-life

• Biological potency in different tissues and contexts

Oligomerization States

The search results indicate that mouse IP-10 exists in different oligomeric forms which are important for its in vivo activity . These different states may allow for fine-tuning of IP-10's biological effects.

Species Differences

Both mouse and human IP-10 can form oligomers, but their tetrameric structures differ significantly . This structural divergence may contribute to species-specific aspects of IP-10 function that should be considered when translating findings between mouse models and human disease.

Experimental Applications

Understanding IP-10 oligomerization could inform the development of:

• Modified IP-10 variants with altered oligomerization properties

• Therapeutic approaches targeting specific oligomeric forms

• Improved assays that distinguish between different oligomeric states

The diverse oligomeric states of IP-10 represent an important consideration for researchers studying its biological effects in mouse models.

How do mouse and human IP-10 differ, and what are the implications for translational research?

Several important differences between mouse and human IP-10 affect the translational relevance of mouse studies:

Structural and Sequence Differences

• Mouse IP-10 shares only approximately 67% amino acid sequence identity with human IP-10

• The tetrameric structure of mouse IP-10 differs from human IP-10, potentially affecting receptor interactions

• These structural differences may impact binding affinity, signaling potency, and biological outcomes

Receptor Biology

While both mouse and human IP-10 signal through CXCR3, species-specific differences exist in:

• Receptor expression patterns across cell types

• Downstream signaling pathway activation

• Receptor internalization and recycling dynamics

Immune System Variations

Fundamental differences between mouse and human immune systems include:

• Different leukocyte subpopulation distributions

• Baseline cytokine/chemokine networks

• Innate immune sensing mechanisms

• Response kinetics to inflammatory stimuli

Disease Context

• Mouse models rarely recapitulate all aspects of human disease

• The relative contribution of IP-10 to pathogenesis may differ between species

• Timing and context of IP-10 expression varies between mouse models and human conditions

Technical Considerations

• Detection reagents may have different affinities for mouse vs. human IP-10

• Standard laboratory mouse strains do not reflect human genetic diversity

• Housing conditions affect mouse immune parameters in ways that don't translate to humans

Strategies to Improve Translation

To enhance translational relevance:

• Conduct parallel studies in mouse models and human samples

• Validate key findings across multiple mouse strains

• Use humanized mouse models where appropriate

• Confirm critical mechanistic findings with human cells in vitro

• Consider comparative studies examining both mouse and human IP-10 proteins

By acknowledging these differences and adopting mitigating strategies, researchers can more appropriately interpret mouse IP-10 data in human disease contexts.

What specialized detection methods are available for studying mouse IP-10 in complex biological samples?

Researchers have access to several specialized methods for detecting and characterizing mouse IP-10 in complex samples:

High-Sensitivity Immunoassay Platforms

The Simoa (Single Molecule Array) platform offers ultrasensitive detection of mouse IP-10, potentially providing:

• Lower limits of detection than conventional ELISAs

• Ability to measure IP-10 in cerebrospinal fluid and other limited samples

• Detection of IP-10 in contexts where levels may be below the threshold of standard assays

Multiplexed Detection Systems

• Bead-based multiplex immunoassays enable simultaneous quantification of IP-10 alongside other cytokines/chemokines

• These systems allow for comprehensive immune profiling with limited sample volumes

• Correlation analyses between IP-10 and other inflammatory mediators become possible

Imaging-Based Detection

• Immunohistochemistry and immunofluorescence techniques visualize IP-10 distribution in tissue contexts

• In situ hybridization can identify cells actively producing IP-10 mRNA

• Multiplex immunofluorescence can simultaneously detect IP-10, CXCR3, and responding cell types

Functional Assays

Beyond simply measuring IP-10 levels, functional assays assess biological activity:

• Chemotaxis assays using CXCR3+ cells to measure bioactive IP-10

• Receptor binding assays to determine affinity for CXCR3

• Signaling assays (calcium flux, phosphorylation cascades) to assess downstream pathway activation

Analytical Validation Parameters

When implementing these methods, researchers should consider performance characteristics such as:

• Sensitivity and dynamic range

• Inter- and intra-assay precision (exemplified by CV% values in the 4-10% range)

• Recovery rates in different biological matrices (typically 90-110% in optimized assays)

• Specificity and cross-reactivity with related chemokines

By selecting appropriate detection methods and understanding their analytical limitations, researchers can generate more reliable and interpretable data on mouse IP-10 in complex biological systems.