LAIR1 Mouse

What is LAIR1 and what are its key characteristics in mice?

LAIR1 (also known as CD305) is a 46 kDa inhibitory receptor of the Ig superfamily structurally related to inhibitory members of KIR and ILT/CD85 families. The mouse protein is a 253 amino acid type I transmembrane protein containing a 21 aa signal sequence, a 124 aa extracellular domain (ECD), a 20 aa transmembrane domain, and a 98 aa cytoplasmic domain . The ECD includes one C2-type Ig-like domain and potential glycosylation sites. Mouse and human LAIR-1 share approximately 40% homology while maintaining potent inhibitory capacity and the ability to bind collagen and collagen-like molecules .

LAIR1 is expressed on multiple immune cell types, including NK cells, T cells, B cells, monocytes, immature neutrophils, dendritic cells, and most thymocytes . Tyrosine phosphorylation of cytoplasmic ITIM motifs results in recruitment of phosphatases and down-regulation of signaling through activating receptors .

What types of LAIR1 mouse models are available for research?

Several LAIR1 mouse models have been developed for immunological research:

• LAIR1 knockout mice (LAIR1−/−): Complete deletion of LAIR1 expression, generated to study the role of LAIR1 in immune regulation .

• Hematopoietic-specific human LAIR1 transgenic mice: Express human LAIR1 specifically in hematopoietic cells, generated at the Transgenic Core Facility at UT Southwestern .

• Vav-Cre human LAIR1 transgenic mice in mouse LAIR1−/− background: Created to avoid interference from mouse LAIR1 during tumor development studies. The transgenic LAIR1 is expressed on all lineages of hematopoietic cells in these mice .

• Humanized mouse models for LAIR1 studies: NSG-SGM3 mice with transplanted human CD34+ cells to establish human immune cell chimerism, used for studying human LAIR1 function in tumor development .

What are the baseline phenotypic characteristics of LAIR1−/− mice?

LAIR1−/− mice display several distinctive characteristics while remaining generally healthy:

• General health: LAIR1−/− mice are healthy and fertile with normal longevity .

• Immune cell alterations: These mice show increased numbers of splenic B cells, T regulatory cells, and dendritic cells compared to wild-type mice .

• Age-dependent changes: As LAIR1−/− mice age, their splenic T cell population shows a higher frequency of activated and memory T cells .

• Antibody production: LAIR1−/− mice have lower serum levels of IgG1 .

• Immune responses: In response to T-dependent immunization with TNP-OVA, these mice switch less efficiently to antigen-specific IgG2a and IgG2b, while switching to IgG1 is not affected .

• Normal trafficking: LAIR1+/+ and LAIR1−/− T cells traffic with equal proficiency to peripheral lymphoid organs, suggesting normal lymphocyte trafficking .

How should researchers design experiments to study LAIR1's role in neutrophilic inflammation?

When designing experiments to study LAIR1's role in neutrophilic inflammation, researchers should implement the following methodological approach:

• Model selection: Use established models of neutrophil-driven inflammation such as:

  • Respiratory syncytial virus (RSV) infection

  • Cigarette smoke exposure

  • Direct CXCL1 chemokine instillation

• Experimental groups:

  • LAIR1−/− mice vs. wild-type littermate controls

  • Consider age and sex matching (8-16 week-old male and female mice recommended)

  • Include LAIR1-Fc administration groups to block ligand-induced LAIR1 activation

• Key readouts:

  • Total and differential cell counts in bronchoalveolar lavage (BAL) fluid

  • Flow cytometric analysis of neutrophil activation markers (CD11b, CD62L, CD182)

  • LAIR1 expression on circulating vs. tissue-infiltrated neutrophils

  • Weight loss monitoring for disease severity

  • Cytokine and chemokine measurements in BAL fluid

• Timeline considerations:

  • Monitor both early (neutrophil-dominated) and later (lymphocyte-dominated) phases of inflammation

  • For RSV infection: day 1 and day 5 post-infection are critical timepoints

  • For cigarette smoke exposure: daily monitoring with progressive increase in exposure dose is recommended

• Additional controls:

  • Verify baseline neutrophil numbers and activation states in blood and bone marrow

  • Confirm LAIR1 expression patterns before and after inflammatory challenge

This experimental approach will enable comprehensive analysis of LAIR1's role in regulating neutrophil recruitment, activation, and inflammatory resolution.

What techniques are most effective for analyzing LAIR1's impact on tumor microenvironment?

To effectively analyze LAIR1's impact on the tumor microenvironment, researchers should employ a multi-faceted approach combining several advanced techniques:

• Single-cell RNA sequencing (scRNAseq):

  • Apply to CD45+ immune cells isolated from tumor tissues

  • Use unsupervised clustering to identify distinct immune cell populations

  • Compare percentages of immune cell types between treatment groups

  • Statistical analysis using Chi-square test is recommended for assessing significance of percentage changes

• Flow cytometry:

  • Comprehensive immunophenotyping of tumor-infiltrating immune cells

  • Key populations to analyze include:

    • CD4+ T cell subsets (naïve, memory, regulatory)

    • CD8+ T cell subsets (naïve, cytotoxic)

    • Macrophage polarization (inflammatory vs. pro-tumor)

    • Dendritic cell subsets (migratory DCs, plasmacytoid DCs)

    • Myeloid-derived suppressor cells (M-MDSC)

• Functional assays:

  • T cell proliferation assays using cells isolated from cancer patients

  • In vitro cultures to assess activity of multiple immune cell types in response to LAIR1 modulation

  • Analysis of cytokine production profiles

• In vivo experimental endpoints:

  • Tumor volume measurements (calculated as (length × width × width)/2)

  • Survival analysis using Kaplan-Meier curves

  • Metastasis quantification, particularly focusing on liver metastasis which showed significant reduction with anti-LAIR1 treatment

• Comparison of models:

  • Transgenic mouse models expressing human LAIR1 on immune cells

  • Humanized mouse models with human immune cell reconstitution

  • Analysis of both primary tumor growth and metastatic spread

This comprehensive approach enables detailed characterization of how LAIR1 modulation affects the complex cellular interactions within the tumor microenvironment.

How can researchers distinguish the effects of mouse versus human LAIR1 in experimental models?

Distinguishing the effects of mouse versus human LAIR1 in experimental models requires careful experimental design and specialized methods:

• Generation of appropriate transgenic models:

  • Develop human LAIR1 transgenic mice in mouse LAIR1−/− background (as used in the Vav-Cre human LAIR1 transgenic system)

  • This eliminates interference from endogenous mouse LAIR1 while allowing study of human LAIR1 function

  • Verify transgene expression on all appropriate hematopoietic lineages using flow cytometry

• Cross-species reactivity considerations:

  • Recognize that mouse collagen can bind and activate human LAIR1, enabling functional studies in transgenic models

  • Test species-specific antibodies to confirm they recognize only human or mouse LAIR1

  • When using anti-human LAIR1 antibodies in humanized models, consider that both human and mouse collagen exist, potentially affecting interpretation

• Humanized mouse systems:

  • Use NSG-SGM3 mice (with transgenic expression of human SCF, GM-CSF, and IL-3) to enable better engraftment of human myeloid cells

  • Transplant human CD34+ cells and confirm human CD45+ chimerism (with human myeloid and T cells) in blood before experiments

  • Implant human tumor cell lines (e.g., MDA-MB-231) to create a fully humanized disease model

• Species-specific reagents:

  • Use antibodies specific for mouse LAIR1 for detection in mouse tissues (e.g., Rabbit Anti-Mouse LAIR1 Monoclonal Antibody for Western blot)

  • Employ human-specific anti-LAIR1 antibodies (e.g., h219-LLG) for functional studies in human LAIR1 transgenic models

  • Verify specificity of detection in experimental tissues (as shown in Figure 1 of search result 1)

• Experimental controls:

  • Include wild-type mice, mouse LAIR1−/− mice, and human LAIR1 transgenic mice in the same experiments

  • Confirm that any observed effects of anti-human LAIR1 antibodies occur only in mice expressing human LAIR1

This approach allows researchers to dissect the distinct functions of human versus mouse LAIR1 while leveraging the experimental advantages of mouse models.

How does LAIR1 deficiency affect immune responses in respiratory infection models?

LAIR1 deficiency significantly impacts immune responses in respiratory infection models, particularly affecting neutrophilic inflammation:

• Enhanced airway inflammation:

  • LAIR1−/− mice show increased total leukocyte influx into the airways following RSV infection

  • This enhancement is observed at both early and late timepoints post-infection

• Time-dependent immune cell recruitment:

  • Early in infection (day 1), increased cell numbers are primarily due to enhanced neutrophil recruitment

  • At day 5 post-infection, lymphocytes constitute the main infiltrating population in LAIR1−/− mice

• Normal macrophage responses:

  • No significant differences in macrophage recruitment between LAIR1−/− and wild-type mice

• Cytokine and chemokine production:

  • Despite enhanced leukocyte recruitment, levels of neutrophil chemoattractant CXCL1 and inflammatory cytokine IL-6 were not increased in BAL fluid of RSV-infected LAIR1−/− mice

  • This suggests LAIR1 primarily affects cell trafficking rather than cytokine production

• Neutrophil expression patterns:

  • In unchallenged wild-type mice, circulating neutrophils do not express LAIR1, while tissue-infiltrated neutrophils do

  • Upon RSV infection, circulating neutrophils begin expressing LAIR1

  • Airway-infiltrated neutrophils express LAIR1 and show high activation (CD11b upregulation and CD62L shedding)

These findings indicate LAIR1 functions as a regulator of immune cell trafficking and activation during respiratory infections, particularly limiting neutrophil and lymphocyte recruitment to control inflammation.

What is LAIR1's role in cancer immunotherapy based on preclinical mouse models?

Preclinical mouse models reveal LAIR1 as a promising target for cancer immunotherapy through multiple mechanisms:

• Tumor growth inhibition:

  • Anti-LAIR1 humanized antagonist antibody (h219) significantly inhibits tumor development in human LAIR1 transgenic mice

  • Treatment with h219-LLG antibody prolongs survival of transgenic mice implanted with B16 mouse tumor cells

• Metastasis reduction:

  • In humanized mouse models, h219-LLG treatment clearly decreased liver metastasis of human breast cancer cells

  • This occurred even in cases where the primary tumor growth was not significantly affected

• Alteration of tumor immune microenvironment:

  • Single-cell RNA sequencing of tumor-infiltrating immune cells revealed that LAIR1 blockade:

    • Increased percentages of CD4 memory T cells and inflammatory macrophages

    • Decreased pro-tumor macrophages, regulatory T cells (Tregs), and plasmacytoid dendritic cells

• Effects on human immune cells in humanized models:

  • h219-LLG elevated percentages of total human CD3+ T cells

  • Decreased CD4+CD25+CD127low/- Tregs and myeloid-derived suppressor cell (MDSC) populations in tumors

  • The anti-tumor effect resulted from inhibiting LAIR1 signaling specifically in human immune cells, not direct effects on tumor cells

• Comparison with soluble LAIR2:

  • LAIR2 (soluble ortholog of LAIR1 found in humans but not mice) inhibits tumor development through competitive binding to collagen

  • Anti-LAIR1 antagonist antibodies work through a different mechanism by directly binding LAIR1 to block signaling

  • Anti-LAIR1 antibodies may provide more effective inhibition of LAIR1-mediated immunosuppression than LAIR2

These findings position LAIR1 blockade as a promising strategy for cancer immunotherapy that works by remodeling the immune composition of the tumor microenvironment.

How does LAIR1 modulate inflammatory responses in cigarette smoke exposure models?

LAIR1 plays a critical role in moderating inflammatory responses in cigarette smoke exposure models, affecting both disease severity and immune cell recruitment:

These findings establish LAIR1 as an important immune checkpoint that prevents excessive inflammatory responses to environmental insults such as cigarette smoke.

How should researchers interpret the mild phenotype of LAIR1−/− mice despite LAIR1's role as an inhibitory receptor?

The relatively mild phenotype of LAIR1−/− mice at baseline requires nuanced interpretation:

• Compensatory mechanisms:

  • The mild phenotype likely reflects redundancy in inhibitory receptor systems

  • Any adverse effects of LAIR1 absence may be balanced by other inhibitory receptors

  • The immune system employs multiple overlapping regulatory mechanisms to maintain homeostasis

• Context-dependent importance:

  • While LAIR1−/− mice remain healthy under standard conditions, they show exaggerated responses under specific challenges

  • Enhanced airway inflammation during RSV infection and cigarette smoke exposure reveals LAIR1's importance in controlling inflammation under stress conditions

  • This context-dependency is common among immune regulatory molecules

• Subtle baseline alterations:

  • Despite appearing generally healthy, LAIR1−/− mice do show alterations in splenic immune cell populations

  • Increased numbers of B cells, T regulatory cells, and dendritic cells indicate subtle immune dysregulation

  • Age-dependent accumulation of activated and memory T cells suggests gradual impact over time

• Antibody production changes:

  • Lower serum IgG1 levels and altered antibody class switching indicate LAIR1 influences B cell function

  • Less efficient switching to IgG2a and IgG2b in response to T-dependent immunization reveals specific immunological impacts

• Evolutionary perspective:

  • The relatively mild phenotype may reflect evolutionary selection for redundancy in immune regulation

  • Critical immune checkpoints often have overlapping functions to prevent catastrophic dysregulation if any single system fails

This interpretation framework helps researchers understand why inhibitory receptor knockouts may not present dramatic phenotypes until challenged, and guides experimental design toward appropriate stress or disease models.

What technical challenges must be addressed when comparing anti-LAIR1 antibodies to LAIR2 in cancer immunotherapy approaches?

Several technical challenges must be addressed when comparing anti-LAIR1 antibodies to LAIR2 as cancer immunotherapy approaches:

• Mechanism of action differences:

  • LAIR2 (soluble ortholog of LAIR1) functions by competitively binding to collagen, preventing LAIR1-collagen interactions

  • Anti-LAIR1 antibodies directly bind the receptor to block signaling

  • Experimental designs must account for these distinct mechanisms when comparing efficacy

• Target saturation considerations:

  • Collagen is abundant throughout the body, so LAIR2 may require higher dosing to saturate targets compared to anti-LAIR1 antibodies

  • Dose-response studies should be carefully designed to achieve equivalent target engagement

• Cross-species reactivity issues:

  • In humanized mouse models, both human and mouse collagens exist

  • LAIR2 can bind both human and mouse collagens

  • Anti-human LAIR1 antibodies recognize only human LAIR1

  • This discrepancy may lead to underestimation of anti-LAIR1 antibody efficacy in humanized models

• Biodistribution differences:

  • LAIR2 may be sequestered by binding to extratumoral collagen

  • Anti-LAIR1 antibodies target the receptor on immune cells directly

  • Pharmacokinetic/pharmacodynamic studies should assess these differences

• Ligand coverage differences:

  • While LAIR2 binds collagen, it's unclear whether it binds all potential LAIR1 ligands

  • Anti-LAIR1 antibodies would block interactions with all ligands

  • Comprehensive binding studies are needed to fully understand these differences

Addressing these challenges through careful experimental design will provide more accurate comparisons between these two therapeutic approaches and may guide optimization of clinical translation.

What future research directions should be prioritized for LAIR1 mouse models based on current findings?

Based on current findings, several high-priority research directions emerge for LAIR1 mouse models:

• Combination immunotherapy approaches:

  • Investigate anti-LAIR1 antibodies in combination with established checkpoint inhibitors (PD-1/PD-L1, CTLA-4)

  • Determine if these combinations produce synergistic anti-tumor effects

  • Study whether LAIR1 blockade can overcome resistance to existing immunotherapies

• Mechanistic studies of metastasis inhibition:

  • Further investigate why LAIR1 blockade more strongly affects metastasis than primary tumor growth

  • Explore cellular and molecular mechanisms underlying this differential effect

  • Develop models specifically optimized for studying the impact on the metastatic process

• LAIR1's role in chronic inflammatory diseases:

  • Extend studies from acute models (RSV, cigarette smoke) to chronic inflammatory disease models

  • Investigate potential connections to human conditions like COPD, asthma, and other chronic inflammatory disorders

  • Determine if long-term LAIR1 modulation affects disease progression

• Neutrophil-specific LAIR1 function:

  • Develop neutrophil-specific LAIR1 knockout or transgenic models

  • Distinguish neutrophil-intrinsic effects from those on other immune cells

  • Investigate the dynamic regulation of LAIR1 expression during neutrophil activation and tissue infiltration

• Biomarker development for personalized approaches:

  • Identify potential biomarkers that predict response to LAIR1-targeted therapies

  • Investigate whether LAIR1 expression levels on specific immune populations correlate with response

  • Determine if collagen levels or other LAIR1 ligands in the tumor microenvironment affect therapeutic efficacy

• Humanized models with patient-derived immune cells:

  • Develop more sophisticated humanized models using patient-derived immune cells

  • Study variability in LAIR1 function across different cancer patients

  • Test personalized approaches to LAIR1-targeted therapy

These research directions would significantly advance understanding of LAIR1 biology while accelerating clinical translation of LAIR1-targeted therapies.

What protocols yield optimal results for detecting LAIR1 expression in mouse tissues?

For optimal detection of LAIR1 expression in mouse tissues, researchers should follow these methodological approaches:

• Western blot detection:

  • Use 2 μg/mL of Rabbit Anti-Mouse LAIR1 Monoclonal Antibody (e.g., Catalog # MAB10092)

  • Follow with HRP-conjugated Anti-Rabbit IgG Secondary Antibody

  • Expect to detect specific bands for LAIR1 at approximately 36-14 kDa

  • Recommended tissues/cells: RAW 264.7 mouse monocyte/macrophage cell line and mouse thymus tissue

  • Conduct under reducing conditions using appropriate immunoblot buffers

• Flow cytometry analysis:

  • Fresh isolation of cells is critical for optimal detection

  • Compare expression between circulating cells (blood) and tissue-infiltrated cells

  • Include activation markers (CD11b, CD62L, CD182) to correlate with LAIR1 expression

  • Consider analyzing both unstimulated and stimulated (e.g., with LPS or during infection) conditions

• Sample preparation considerations:

  • For storage and reconstitution of antibodies:

    • Use a manual defrost freezer and avoid repeated freeze-thaw cycles

    • Store at -20 to -70°C for 12 months from receipt date

    • After reconstitution, store at 2-8°C for up to 1 month under sterile conditions

    • For longer storage, keep at -20 to -70°C for up to 6 months under sterile conditions

• Tissue-specific considerations:

  • Expression is highest on immune cells, particularly in lymphoid tissues

  • For lung studies, bronchoalveolar lavage provides good access to infiltrating immune cells

  • For tumor studies, careful dissociation protocols that preserve surface markers are essential

• Single-cell RNA sequencing approach:

  • For comprehensive analysis of LAIR1 expression across multiple cell types

  • Particularly valuable in heterogeneous tissues like tumors

  • Allows correlation of LAIR1 expression with broader transcriptional programs

These optimized protocols will ensure reliable detection of LAIR1 across different experimental contexts.

How should researchers design tumor studies in LAIR1-modified mouse models to maximize translational relevance?

To maximize translational relevance in tumor studies using LAIR1-modified mouse models, researchers should implement the following design principles:

• Model selection and development:

  • For studying human LAIR1-targeted therapies: use Vav-Cre human LAIR1 transgenic mice in mouse LAIR1−/− background

  • For humanized studies: transplant human CD34+ cells into NSG-SGM3 mice (with transgenic expression of human SCF, GM-CSF, and IL-3) to enable better engraftment of human myeloid cells

  • Verify human immune cell chimerism (≥3 months post-transplant) before tumor implantation

• Tumor model selection:

  • For syngeneic models: B16 melanoma in human LAIR1 transgenic mice

  • For human tumor models: MDA-MB-231 human breast cancer cells in humanized mice

  • Consider both subcutaneous implantation and metastasis models

• Treatment protocol design:

  • Begin treatment when tumors reach 50-60 mm³ to better reflect clinical scenarios

  • Include both short-term (tumor growth) and long-term (survival) endpoints

  • Measure both primary tumor growth and metastatic spread (particularly liver metastasis)

• Comprehensive immune profiling:

  • Perform single-cell RNA sequencing of tumor-infiltrating immune cells

  • Conduct detailed flow cytometric analysis of immune cell populations and activation states

  • Compare results with human cancer samples when possible

• Experimental controls and blinding:

  • Use sex- and age-matched (4-8 weeks) mice randomly allocated to treatment groups

  • Ensure experimenters are blinded to treatment conditions during tumor size measurement

  • Include both wild-type and mouse LAIR1−/− controls alongside human LAIR1 transgenic mice

• Clinical parameter assessment:

  • Monitor tumor size calculated as (length × width × width)/2

  • Track survival using Kaplan-Meier analysis

  • Evaluate metastatic burden through appropriate tissue analysis

This comprehensive approach enhances the translational value of preclinical findings and increases the probability that results will predict clinical outcomes in human patients.

What are the key considerations when interpreting contradictory findings in LAIR1 research?

When interpreting contradictory findings in LAIR1 research, researchers should consider several key factors:

• Model-specific differences:

  • Results may differ between:

    • Complete LAIR1 knockout vs. cell-specific deletion

    • Mouse LAIR1 studies vs. human LAIR1 transgenic models

    • Acute vs. chronic disease models

  • Mouse and human LAIR1 share only ~40% homology despite similar inhibitory capacity

• Context-dependent LAIR1 expression:

  • Expression patterns differ significantly between:

    • Circulating vs. tissue-infiltrated neutrophils

    • Resting vs. activated immune cells

    • Different disease states and inflammatory contexts

  • These dynamic expression patterns may explain apparently contradictory functional findings

• Compensatory mechanisms:

  • LAIR1−/− mice are generally healthy despite LAIR1's role as an inhibitory receptor

  • Other inhibitory receptors likely compensate for LAIR1 absence

  • The balance of these compensatory mechanisms may differ between experimental systems

• Methodological variations:

  • Different antibody clones may have distinct functional effects

  • Variation in experimental readouts (e.g., in vitro vs. in vivo, different timepoints)

  • Differences in genetic background of mouse strains used

• Target cell heterogeneity:

  • LAIR1 affects multiple immune cell types differently:

    • Enhanced neutrophil recruitment in LAIR1−/− mice during inflammation

    • Changes in T regulatory cells and dendritic cells in tumor models

    • Different effects on macrophage polarization

  • Experimental focus on different cell populations may yield apparently contradictory results

When confronted with contradictory findings, researchers should carefully evaluate these factors and consider designing experiments that directly address the specific variables that might explain the discrepancies, rather than simply dismissing conflicting results.