IL 13 Mouse

What is mouse IL-13 and what are its key structural characteristics?

Mouse IL-13 is an immunoregulatory cytokine primarily produced by activated Th2 cells, mast cells, and NK cells. It belongs to the Th2 cytokine family and plays crucial roles in various physiological and pathological processes. Structurally, mouse IL-13 is a 131-amino acid protein that is secreted as an approximately 14-kDa protein . The active form of recombinant mouse IL-13 typically spans from Ser26 to Phe131 of the full protein sequence .

The protein exhibits cross-species reactivity with human IL-13, although there are functional differences between the species . Unlike human IL-13, mouse IL-13 expression is more clearly associated with the Th2 cytokine pattern . For experimental applications, mouse IL-13 is available in both carrier-containing (with BSA) and carrier-free formulations, with specific reconstitution and storage recommendations to maintain bioactivity .

What detection methods are most effective for quantifying mouse IL-13 in biological samples?

Enzyme-linked immunosorbent assay (ELISA) is the gold standard for quantifying mouse IL-13 in biological samples. The mouse IL-13 solid-phase sandwich ELISA utilizes a matched antibody pair system where a target-specific antibody is pre-coated in microplate wells . This methodology offers several advantages:

• Sample versatility: Effectively quantifies IL-13 in mouse serum, buffered solutions, and cell culture media

• Specificity: Exclusively recognizes both natural and recombinant mouse IL-13, with some cross-reactivity observed in human and rat samples

• Sensitivity: Detects physiologically relevant concentrations through signal amplification

• Reliability: Undergoes rigorous validation for criteria such as sensitivity, specificity, precision, and lot-to-lot consistency

For experimental design, researchers should note that the detection principle relies on a target-specific antibody pre-coated in microplate wells that captures IL-13, followed by addition of a detector antibody and substrate solution to produce measurable signal proportional to IL-13 concentration .

How does IL-13 influence antibody production and B cell responses in mice?

IL-13 enhances antibody production in mice through direct effects on B cells, contrary to earlier reports suggesting mouse B cells were unresponsive to IL-13. In vivo administration of recombinant mouse IL-13 via osmotic pump during immunization with chicken RBCs enhances plasma levels of total IgG1, IgG2a, and IgG2b, as well as antigen-specific immunoglobulins .

At the cellular level, IL-13 acts through multiple mechanisms:

• Direct B cell stimulation: IL-13 directly stimulates mouse B cells, causing extended survival and higher antibody levels

• Enhanced antibody secretion: In cultures with anti-CD40-stimulated sIgD+ B cells, IL-13 increases production of IgM and, to a lesser extent, IgG1, IgG2a, IgG2b, and IgG3

• Cell survival promotion: IL-13 increases the numbers of both total and antibody-secreting B cells in highly purified B cell populations (>99.5% pure)

• Independent of IL-4: These effects occur even in the presence of anti-IL-4 antibodies, indicating a distinct mechanism from IL-4

Importantly, IL-13 does not induce class switching or increase CD23 expression, differentiating its mechanism from IL-4. It also does not enhance B cell proliferation as measured by intracellular fluorescence label dilution, suggesting that its primary effect is on B cell survival rather than proliferation .

What is the relationship between IL-13 and inflammatory processes in mouse disease models?

IL-13 exhibits complex roles in inflammatory processes, with both pro-inflammatory and anti-inflammatory effects depending on the disease context:

Anti-inflammatory effects:

• Inhibits expression of inflammatory cytokines including IL-1β, TNF-α, IL-6, and IL-8 in monocytes and macrophages

• Modulates immune responses to limit excessive inflammation

Pro-inflammatory/pathological roles:

• Promotes allergic airway inflammation and asthma through periostin regulation and goblet cell metaplasia

• Enhances susceptibility to Chlamydia respiratory and genital tract infections

• Induces skin fibrosis in atopic dermatitis models through thymic stromal lymphopoietin

The dual nature of IL-13 makes it a critical target for therapeutic interventions. Research shows that blocking IL-13 activity inhibits asthma pathophysiology , while targeted deletion of IL-13 in mice results in impaired Th2 cell development and compromises the expulsion of gastrointestinal parasites .

What role does IL-13 play in neuronal function and cognitive processes in mice?

Recent research has revealed unexpected neuronal functions of IL-13 beyond its established immunological roles. IL-13 and its receptor IL-13Rα1 are expressed as neuronal synaptic proteins in mouse, rat, and human brains in an activity-dependent manner under normal physiological conditions . This neuronal expression has significant functional implications:

Synaptic signaling mechanisms:

• IL-13 engagement upregulates phosphorylation of NMDAR and AMPAR subunits

• This phosphorylation increases synaptic activity and CREB-mediated transcription

• IL-13 functions as a physiological modulator of synaptic physiology of neuronal origin

Cognitive function:

• IL-13-deficient mice demonstrate significant impairment in working memory and attenuated reference memory

• These memory functions are essential for effective complex learning

• During learning processes, wild-type mice increase CD4+ T cells in the meninges and IL-13 production

Mechanistic pathway:

• IL-13 stimulates primary astrocytes to produce brain-derived neurotrophic factor (BDNF)

• BDNF is known to foster cognitive functions

• Morris water maze-trained wild-type mice show increased astrocyte-produced glial fibrillary acidic protein (GFAP) in the hippocampus, which is impaired in IL-13-deficient mice

This research suggests that Th2 cytokines, including both IL-4 and IL-13, are involved in cognitive functions through interactions with astrocytes in the meninges and hippocampus, opening potential therapeutic approaches for neurological disorders .

How does IL-13 contribute to neuroprotection in traumatic brain injury (TBI) mouse models?

IL-13 demonstrates significant neuroprotective properties in traumatic brain injury (TBI) models:

Expression pattern in TBI:

• Increased IL-13 is a hallmark of TBI in male mice

• Similar upregulation is observed in two distinct cohorts of human TBI patients

• Upregulation occurs in human brain samples and cerebrospinal fluid (CSF)

Neuroprotective mechanisms:

• IL-13 upregulation protects neurons from excitotoxic death

• It functions as a physiological modulator of synaptic physiology with implications for neuronal survival under injury conditions

• The neuroprotection provided through IL-13 upregulation represents a potential entry point for interventions in TBI pathophysiology

These findings suggest that the traditionally immune-associated cytokine IL-13 has critical functions in the central nervous system, particularly in response to injury. This dual role makes IL-13 an intriguing target for developing neuroprotective strategies.

What are the optimal reconstitution and storage conditions for recombinant mouse IL-13?

Proper handling of recombinant mouse IL-13 is critical to maintain its bioactivity for experimental applications. The following protocols are recommended based on the formulation:

Standard formulation (with carrier protein):

• Formulation: Lyophilized from a 0.2 μm filtered solution in PBS with BSA as a carrier protein

• Reconstitution: Reconstitute at 50 μg/mL in sterile PBS containing at least 0.1% human or bovine serum albumin

• Shipping: Product is shipped at ambient temperature

• Storage: Upon receipt, store immediately at recommended temperature

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

Carrier-free formulation:

• Formulation: Lyophilized from a 0.2 μm filtered solution in PBS without BSA

• Reconstitution: Reconstitute 5 μg vials at 50 μg/mL in sterile PBS; reconstitute 25 μg or larger vials at 100 μg/mL in sterile PBS

• Shipping: Product is shipped at ambient temperature

• Storage: Upon receipt, store immediately at recommended temperature

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

The carrier-free version is recommended for applications where the presence of BSA could interfere, while the standard formulation with BSA is preferred for cell or tissue culture applications or as an ELISA standard .

What is the effective dose range of mouse IL-13 for in vitro bioassays?

For in vitro bioassays, mouse IL-13 demonstrates activity within specific dose ranges depending on the experimental system:

Bioassay effective dose:

• The ED50 (effective dose for 50% maximal response) is typically in the range of 0.75-3 ng/mL

• This concentration range is effective for stimulating biological responses in various cell types

Application-specific considerations:

• For B cell survival and antibody production assays, concentrations that enhance antibody secretion without inducing proliferation should be used

• For neuronal studies, concentrations should be optimized based on the specific readout (phosphorylation, transcription, etc.)

• For in vivo administration via osmotic pumps, delivery rates should be calculated to achieve physiologically relevant tissue concentrations

Researchers should validate the activity of each lot of recombinant protein in their specific experimental system, as activity may vary between different cell types and assay conditions.

What are the key phenotypic differences between IL-13 knockout mice and wild-type counterparts?

IL-13 knockout mice display several distinct phenotypic differences from their wild-type counterparts across multiple physiological systems:

Immune system phenotypes:

• Impaired Th2 cell development

• Compromised ability to expel gastrointestinal parasites

• Altered antibody production profiles

Neurological phenotypes:

• Significantly impaired working memory

• Attenuated reference memory, affecting complex learning

• Inability to increase CD4+ T cells in the meninges during learning processes

• Impaired astrocyte activation in the hippocampus during learning tasks

Response to disease challenges:

• Altered susceptibility to allergic airway inflammation

• Modified responses to parasitic, bacterial, and viral infections

• Changed inflammatory profiles in models of asthma and atopic dermatitis

These phenotypic differences highlight the multifaceted roles of IL-13 beyond its traditional classification as a Th2 cytokine, revealing its importance in both immunological and neurological functions.

How can researchers effectively distinguish between IL-4 and IL-13 functions in mouse models?

Distinguishing between IL-4 and IL-13 functions presents a significant challenge due to their overlapping biological activities and shared receptor components. Researchers can employ several strategies to differentiate their specific roles:

Genetic approaches:

• Compare single knockout models (IL-4 KO vs. IL-13 KO) with double knockout mice

• Use conditional knockout models with tissue-specific deletion

• Employ knock-in models with reporter genes to track expression patterns

Receptor-based discrimination:

• Target the IL-13Rα1 chain, which is unique to the IL-13 receptor complex

• Use antagonistic antibodies specific to either IL-4Rα or IL-13Rα1

• Exploit the differential expression of receptor components across cell types

Functional assays:

• IL-13 does not induce class switching or increase CD23 expression in B cells, unlike IL-4

• IL-13 extends B cell survival without enhancing proliferation, differentiating it from IL-4's effects

• IL-13's effects on B cells occur even in the presence of anti-IL-4 antibodies, indicating distinct mechanisms

Neurological function assessment:

By combining these approaches, researchers can more precisely attribute specific biological functions to either IL-4 or IL-13, advancing our understanding of their unique and overlapping roles in health and disease.