IL 13 Rat

What is IL-13 and what are its primary functions in rat models?

IL-13 is a pleiotropic cytokine secreted by activated Th2 cells with immunoregulatory activities that partially overlap with IL-4. In rat models, IL-13 has been identified as a neuronal, synaptic protein expressed in mouse, rat, and human brains, whose engagement upregulates the phosphorylation of NMDAR and AMPAR subunits and increases synaptic activity and CREB-mediated transcription .

The primary functions of IL-13 in rat models include:

• Neuronal signaling: IL-13 triggers the phosphorylation of glutamate receptors and several presynaptic proteins, increasing synaptic activity and neuronal firing, ultimately driving the phosphorylation of transcription factors including CREB .

• Neuroprotection: IL-13 upregulation has been demonstrated to protect neurons against excitotoxic death, particularly in the context of traumatic brain injury .

• Immune modulation: IL-13 functions as a potent modulator of rat macrophage activities, inhibiting production of proinflammatory cytokines like IL-1β and TNF while enhancing MHC class II and CD4 receptor expression .

• Renal effects: When overexpressed in rats, IL-13 induces minimal change-like nephropathy characterized by proteinuria, hypoalbuminemia, hypercholesterolemia, and fusion of podocyte foot processes .

These diverse functions highlight IL-13's physiological significance across multiple organ systems and its potential as a therapeutic target in various disease models.

How are IL-13 receptor subtypes characterized in rat models?

Two primary IL-13 receptor subtypes have been characterized in rat models, each with distinct properties:

IL-13Rα1:

• Functions as a lower affinity IL-13-binding chain

• Participates in productive signal transduction, enabling cellular responses to IL-13

• When expressed in Ba/F3 cells, results in a sensitive proliferative response to IL-13

• Displays strong enrichment in the postsynaptic fraction of neurons, similar to PSD-95

• Forms functional receptor complexes with IL-4R to mediate IL-13 signaling

IL-13Rα2:

Both receptor genes map to the X chromosome in rats, similar to humans . The differential expression and functional properties of these receptor subtypes likely contribute to tissue-specific responses to IL-13 and represent important considerations for therapeutic targeting of the IL-13 system.

What standard methods are used to study IL-13 expression in rat tissues?

Researchers employ several complementary techniques to study IL-13 expression in rat tissues:

For mRNA detection:

• In situ hybridization: This technique enables visualization of IL-13 mRNA in specific cell populations. Double in situ hybridization using markers of glutamatergic neurons (VGLUT1, VGLUT2) and GABAergic neurons (VGAT) has revealed that IL-13 is expressed in both neuronal subtypes, with higher expression in glutamatergic neurons .

• Real-time PCR with hybridization probes: This quantitative approach measures IL-13 and receptor gene expression, typically normalized to housekeeping genes like β-actin .

For protein detection:

• Immunofluorescence staining: Using validated antibodies against IL-13 and its receptors to visualize protein expression in tissue sections or cultured cells. Multiple antibodies should be used to confirm specificity .

• Western blotting: For quantitative assessment of IL-13 protein levels in tissue homogenates or subcellular fractions .

• Subcellular fractionation: This approach separates neural components (e.g., synaptic vesicles, postsynaptic densities) to determine the distribution of IL-13 and its receptors within cellular compartments .

• Super-resolution microscopy (STED): Provides nanoscale resolution of IL-13 and receptor localization at synapses, allowing precise mapping relative to synaptic markers like PSD-95 and Bassoon .

Critical to all these methods is proper validation, particularly when studying IL-13 in neural tissues. Researchers have validated antibodies using IL-13 knockout mice to confirm specificity and minimize false positives .

How does IL-13 influence neuronal function and synaptic plasticity in rat models?

IL-13 exerts multiple effects on neuronal function and synaptic plasticity in rat models through several mechanisms:

Glutamate receptor regulation:

• IL-13 treatment triggers phosphorylation of NMDAR and AMPAR subunits on epitopes related to surface expression and synaptic insertion .

• This leads to significant increases in surface synaptic NMDAR and AMPAR after 1 hour of treatment, though these effects diminish by 3 hours post-treatment .

• The temporal dynamics suggest a transient modulation of receptor trafficking that could influence synaptic strength.

Signaling cascade activation:

• IL-13 engagement with its receptor activates multiple signaling pathways:

  • Phosphorylation of IL-13Rα1 at Tyr405

  • Activation of ERK1/2 (phosphorylation at Thr202/Tyr204)

  • Phosphorylation of STAT6 and STAT3, known targets of IL-13/IL-13Rα1

  • Massive elevation in phosphorylated CREB (S133) levels

Gene expression regulation:

• IL-13 treatment upregulates nuclear expression of transcription factors ATF-3 and DREAM .

• It increases c-fos-positive neurons and induces expression of multiple immediate-early genes (c-fos, fos-B, egr-1, egr-2, gadd45a, gadd45b) .

Synaptic localization:

• Super-resolution microscopy has revealed that IL-13 is predominantly presynaptic, with its peak distribution located approximately 150 nm away from the PSD-95 peak but overlapping with the Bassoon peak .

• Conversely, IL-13Rα1 is predominantly postsynaptic, with its immunoreactivity largely overlapping with PSD-95 .

These findings collectively demonstrate that IL-13 functions as a physiological modulator of synaptic activity, with effects on receptor trafficking, signaling pathway activation, and activity-dependent gene expression that could contribute to both short-term synaptic modulation and longer-term plasticity.

What mechanisms underlie IL-13-induced nephropathy in rat models?

IL-13 overexpression induces minimal change-like nephropathy in rats through multiple mechanisms affecting podocyte structure and function:

Podocyte injury pathway activation:

• IL-13 transfection leads to significant upregulation of B7-1 (CD80) in glomeruli .

• B7-1 induction in podocytes has been linked to cytoskeletal reorganization and proteinuria development .

• This upregulation is accompanied by increased expression of IL-4Rα and IL-13Rα2, suggesting enhanced IL-13 signaling capacity .

Downregulation of slit diaphragm components:

• IL-13 significantly reduces glomerular gene expression of crucial podocyte structural proteins:

  • Nephrin, a key component of the slit diaphragm

  • Podocin, which interacts with nephrin and regulates filtration function

  • Dystroglycan, which connects the podocyte cytoskeleton to the glomerular basement membrane

• Immunofluorescence staining confirms reduced protein expression of these essential components .

Ultrastructural changes:

• Electron microscopy reveals extensive podocyte foot process fusion (up to 80%) in IL-13-transfected rats .

• These changes occur despite the absence of significant glomerular histological abnormalities by light microscopy .

• The foot process effacement explains the functional defect in glomerular filtration.

Functional consequences:

• The molecular and structural alterations induced by IL-13 result in:

  • Significant albuminuria

  • Hypoalbuminemia

  • Hypercholesterolemia

• This triad of findings closely resembles minimal change nephrotic syndrome in humans.

These findings suggest that IL-13 induces nephropathy by directly affecting podocyte gene expression patterns, disrupting the expression of key proteins necessary for maintaining the glomerular filtration barrier integrity, rather than through immune complex deposition or inflammatory cell infiltration.

How does IL-13 modulate immune responses in rat models of autoimmune encephalomyelitis?

IL-13 exhibits significant immunomodulatory effects in rat models of experimental autoimmune encephalomyelitis (EAE), primarily through macrophage-targeting mechanisms:

Macrophage function modulation:

• Human recombinant IL-13 (hrIL-13) potently alters rat macrophage functions in vitro .

• It inhibits production of proinflammatory cytokines IL-1β and TNF from macrophages .

• Simultaneously, IL-13 enhances macrophage MHC class II and CD4 receptor expression, potentially altering antigen presentation capabilities .

T cell response effects:

• IL-13 displays a slight but reproducible inhibitory effect on the proliferative responses of encephalitogenic myelin basic protein (MBP)-specific T cells when stimulated with thymic APCs .

• This effect suggests modest direct modulation of T cell activation by IL-13.

Disease suppression without global immunosuppression:

• In vivo application of hrIL-13-secreting vector cells into MBP-immunized animals markedly suppresses EAE development .

• This suppression is evidenced by reduction in mean duration, severity, and incidence of disease .

• Importantly, this suppression occurs with only minimal reduction of MBP-directed T cell autoreactivity .

• No alteration in MBP-specific autoantibody production is observed, indicating preservation of B cell function .

These findings demonstrate that IL-13 can attenuate a strictly Th1-initiated immune disease primarily by targeting macrophage/monocyte lineage cells rather than through direct suppression of T or B cell functions . This mechanism offers potential therapeutic advantages by avoiding broad immunosuppression while still effectively modulating inflammatory responses in autoimmune conditions.

What functional differences exist between IL-13Rα1 and IL-13Rα2 in rat experimental models?

IL-13Rα1 and IL-13Rα2 demonstrate substantial functional differences in rat models that impact their roles in IL-13 biology:

Binding characteristics:

• IL-13Rα2 binds IL-13 with high affinity, demonstrating a Kd of 0.5-1.2 nM .

• IL-13Rα1 exhibits lower binding affinity for IL-13 .

• Ba/F3 cells transfected with mIL-13Rα2 express approximately 5000 receptor molecules per cell .

Signal transduction capabilities:

• Despite high-affinity binding, IL-13Rα2 appears incapable of mediating proliferative responses to IL-13 .

• Ba/F3 cells expressing IL-13Rα2 do not proliferate in response to IL-13, and the IL-4 dose response remains unaffected by high IL-13 concentrations .

• In contrast, IL-13Rα1 expression enables cells to mount a sensitive proliferative response to IL-13, indicating productive signal transduction capacity .

Neutralizing activity:

• IL-13Rα2.Fc is approximately 100-fold more effective than IL-13Rα1.Fc in neutralizing IL-13 in vitro .

• This superior neutralizing capacity aligns with IL-13Rα2's higher binding affinity and suggests a potential decoy receptor function.

Subcellular localization in neurons:

• In rat neurons, IL-13Rα1 shows strong enrichment in postsynaptic fractions, mirroring PSD-95 distribution .

• This distinct localization suggests specialized roles in synaptic function.

These differences suggest that the two receptor subtypes play complementary rather than redundant roles, with IL-13Rα1 primarily mediating signal transduction and IL-13Rα2 potentially functioning to regulate IL-13 availability through high-affinity binding without significant downstream signaling .

What are the established methods for overexpressing IL-13 in rat models?

Several effective approaches have been developed for overexpressing IL-13 in rat models, each with specific applications:

In vivo electroporation:

• This technique involves transfection of a mammalian expression vector containing the rat IL-13 gene into the quadriceps muscle .

• The process utilizes electric pulses to facilitate DNA uptake into muscle cells .

• It provides sustained expression of IL-13, leading to elevated circulating levels over extended periods .

• This approach was successfully used to study IL-13-induced minimal change-like nephropathy, resulting in significant albuminuria, hypoalbuminemia, and hypercholesterolemia in transfected rats .

Vector-producing cell implantation:

• Human recombinant IL-13 (hrIL-13)-secreting vector cells can be administered to rats .

• This method has been effectively employed in experimental autoimmune encephalomyelitis (EAE) models .

• It allows for more localized delivery of IL-13, which may be advantageous for studying tissue-specific effects.

• In EAE models, this approach markedly suppressed disease development, reducing duration, severity, and incidence .

Monitoring effectiveness:

• Successful overexpression is typically verified through:

  • Measurement of serum IL-13 levels by ELISA

  • Assessment of phenotypic changes (e.g., proteinuria in nephropathy models)

  • Evaluation of IL-13-responsive gene expression in target tissues

  • Monitoring of relevant physiological parameters (serum albumin, cholesterol)

Experimental considerations:

• The choice of approach depends on research objectives, desired duration of expression, and target tissues.

• Appropriate controls (e.g., empty vector transfection) are essential to distinguish IL-13-specific effects from procedural artifacts.

• The timing of intervention relative to disease induction (e.g., before or after immunization in EAE models) significantly impacts experimental outcomes.

These methodologies have enabled researchers to elucidate IL-13's roles in diverse pathological conditions, from kidney disease to neuroinflammatory disorders, providing valuable insights into potential therapeutic applications.

How can researchers effectively analyze IL-13-mediated signaling in rat neurons?

Analysis of IL-13-mediated signaling in rat neurons requires a multifaceted approach combining various techniques:

Phosphorylation analysis:

• Immunostaining for phosphorylated signaling components provides direct evidence of pathway activation:

  • pIL-13Rα1 (Tyr405) indicates receptor activation

  • pERK1/2 (Thr202/Tyr204) reveals MAPK pathway engagement

  • pCREB (S133) demonstrates transcription factor activation

  • pSTAT6 and pSTAT3 phosphorylation indicates activation of known IL-13/IL-13Rα1 targets

• Western blotting offers quantitative assessment of phosphorylation status across cell populations .

• Time course experiments (e.g., 1h and 3h post-treatment) capture temporal dynamics of signaling activation and resolution .

Receptor trafficking and surface expression:

• Antibodies directed against extracellular epitopes of receptors (GluN1, GluA1) can quantify changes in surface expression following IL-13 treatment .

• This approach revealed IL-13-induced increases in surface synaptic NMDAR and AMPAR expression .

Super-resolution microscopy:

• STED microscopy provides nanoscale localization of IL-13 and its receptors relative to synaptic markers .

• This technique revealed IL-13's predominantly presynaptic localization (overlapping with Bassoon) and IL-13Rα1's postsynaptic enrichment (overlapping with PSD-95) .

Transcriptional responses:

• Immediate-early gene induction serves as a functional readout of signaling:

  • Nuclear localization of transcription factors (ATF-3, DREAM) by immunofluorescence

  • Quantification of c-fos-positive neurons

  • RT-PCR measurement of IEG mRNA levels (c-fos, fos-B, egr-1, egr-2, gadd45a, gadd45b)

Primary neuronal cultures:

• E18-DIV21 cortical neuron cultures provide a controlled system containing primarily neurons (~6% astrocytes, no microglia) .

• These cultures allow for direct assessment of neuronal responses to IL-13 with minimal confounding from other cell types .

By integrating these approaches, researchers can construct a comprehensive picture of IL-13 signaling in neurons, from initial receptor engagement to downstream pathway activation and ultimate transcriptional responses, revealing potential mechanisms for IL-13's effects on neuronal function and synaptic activity.

What controls and validations are essential for IL-13 research in rat models?

Robust controls and validations are critical for generating reliable data in IL-13 research with rat models:

Antibody validation:

• Multiple antibodies should be used to confirm specificity of IL-13 detection .

• Studies have validated both mouse monoclonal and rabbit polyclonal anti-IL-13 antibodies using brain tissue from IL-13−/− mice, demonstrating negligible staining in knockout tissue .

• This validation is particularly important when studying novel expressions of IL-13 in tissues like the brain.

Experimental controls:

• Vehicle-treated controls are essential for all interventional studies .

• For overexpression studies, empty vector transfections provide critical controls for the effects of the procedure itself .

• Time-matched controls should be used when studying temporal dynamics of IL-13 signaling .

Physiological validations:

• Multiple physiological parameters should be monitored to comprehensively assess IL-13 effects:

  • Serum parameters (IL-13, albumin, cholesterol, creatinine)

  • Urine analysis (albumin)

  • Functional assessments relevant to the model (e.g., disease scoring in EAE)

Histological and ultrastructural analysis:

• Both light microscopy and electron microscopy should be employed, as some IL-13-induced changes (like podocyte foot process fusion) may not be visible by light microscopy alone .

Receptor specificity:

• Given the functional differences between IL-13Rα1 and IL-13Rα2, experiments should clarify which receptor mediates observed effects .

• Functional validation of receptor-mediated effects can be performed using receptor-selective reagents or genetic approaches.

Cell type specificity:

• In tissues with heterogeneous cell populations, cell type-specific markers should be used to identify the cellular sources and targets of IL-13 .

• Double in situ hybridization using markers for glutamatergic (VGLUT1, VGLUT2) and GABAergic (VGAT) neurons has revealed cell-specific expression patterns of IL-13 .

Proper implementation of these controls and validations ensures that observed effects are specifically attributable to IL-13 and not to experimental artifacts, antibody cross-reactivity, or non-specific effects of experimental procedures.

How do findings from IL-13 rat models translate to human disease applications?

Findings from IL-13 rat models offer significant translational insights for human diseases, with several important considerations:

Neurological disorders:

• The identification of IL-13 as a neuronal, synaptic protein in rat, mouse, and human brains suggests conserved functions across species .

• Increased IL-13 has been identified as a hallmark of traumatic brain injury (TBI) in both mice and two distinct cohorts of human patients .

• IL-13 upregulation has been observed in several cohorts of human brain samples and in cerebrospinal fluid (CSF), confirming the relevance of rodent findings to human conditions .

• The neuroprotective role of IL-13 against excitotoxic death suggests potential therapeutic applications for human neurodegenerative and acute brain injury conditions .

Kidney disease:

• IL-13-induced minimal change-like nephropathy in rats closely resembles minimal change nephrotic syndrome in humans .

• Both conditions share hallmark features of proteinuria, hypoalbuminemia, hypercholesterolemia, and podocyte foot process fusion .

• The molecular mechanisms involving downregulation of nephrin, podocin, and dystroglycan parallel findings in human nephrotic syndromes .

• These parallels suggest that IL-13-targeting approaches might have therapeutic potential in certain forms of human nephrotic syndrome.

Autoimmune conditions:

• IL-13's protective effects in rat experimental autoimmune encephalomyelitis (EAE) suggest potential applications for human multiple sclerosis and other neuroinflammatory disorders .

• The mechanism involving macrophage modulation rather than direct T cell suppression offers a potentially advantageous approach that might minimize broad immunosuppression in human applications .

Receptor considerations:

While rat models provide valuable insights into IL-13 biology relevant to human diseases, species differences in receptor structures, signaling pathways, and tissue expression patterns must be carefully considered when extrapolating findings to human applications.

What are the most promising research directions for IL-13 in rat neurological models?

Several promising research directions emerge from the current understanding of IL-13 in rat neurological models:

Traumatic brain injury therapeutics:

• Evidence that IL-13 upregulation protects neurons from excitotoxic death positions it as a potential neuroprotective agent for TBI .

• Future research should investigate optimized delivery methods, therapeutic windows, and dose-response relationships for IL-13 in TBI models.

• Combination approaches targeting both IL-13 signaling and other neuroprotective pathways may offer synergistic benefits.

Synaptic plasticity modulation:

• IL-13's ability to trigger phosphorylation of glutamate receptors and increase synaptic activity suggests potential applications in conditions characterized by deficient plasticity .

• Investigation of IL-13's effects on long-term potentiation, long-term depression, and learning/memory paradigms in rats could unveil novel approaches for cognitive enhancement or rehabilitation.

Receptor-specific targeting:

• The distinct localizations and functions of IL-13Rα1 (postsynaptic, signaling) and IL-13Rα2 (high-affinity binding) suggest potential for receptor-selective therapeutic approaches .

• Development of receptor subtype-specific agonists or antagonists could provide more precise tools for modulating IL-13 effects in the CNS.

• Conditional knockout models targeting specific receptor subtypes in defined neuronal populations would help dissect their relative contributions to IL-13's neuronal effects.

Neuroinflammatory disease applications:

• Building on IL-13's success in EAE models , evaluation in other neuroinflammatory conditions (Alzheimer's disease, Parkinson's disease) represents a promising direction.

• Understanding how IL-13 modulates neuroinflammation while preserving or enhancing neuronal function could lead to novel therapeutic strategies that avoid the pitfalls of broad immunosuppression.

Gene therapy approaches:

• In vivo electroporation and vector-producing cell approaches have demonstrated efficacy in rat models .

• Next-generation viral vector systems could enable more targeted, regulatable IL-13 expression in specific brain regions or cell types.

• Such approaches might provide sustained, localized IL-13 effects while minimizing systemic exposure and potential side effects.

These research directions leverage IL-13's unique properties as both a neuronal signaling molecule and immunomodulator, potentially opening new therapeutic avenues for conditions where these systems intersect, such as neurodegenerative diseases, stroke, and traumatic brain injury.

How can apparent contradictions in IL-13 functions across different rat model systems be reconciled?

Apparent contradictions in IL-13 functions across different rat model systems can be reconciled through several key considerations:

Tissue-specific receptor profiles:

• Different tissues express varying levels and proportions of IL-13 receptor subtypes (IL-13Rα1 and IL-13Rα2) .

• IL-13Rα1 mediates productive signaling while IL-13Rα2 binds with high affinity but has limited signaling capacity .

• The ratio of these receptors likely determines the predominant response to IL-13 in a given tissue.

• For example, in neurons, IL-13Rα1 shows strong postsynaptic enrichment, potentially facilitating local signal transduction .

Concentration-dependent effects:

• IL-13 may exert different, even opposing effects at varying concentrations.

• At physiological levels, IL-13 modulates synaptic function by increasing glutamate receptor phosphorylation and surface expression .

• At pathological levels, such as those achieved by overexpression in nephropathy models, IL-13 can induce disease-like manifestations .

Temporal dynamics:

• IL-13's effects demonstrate significant temporal variation.

• Acute effects include rapid phosphorylation of receptors and downstream signaling components .

• These effects may be transient, as seen with the surface expression of NMDAR and AMPAR, which increases at 1 hour but diminishes by 3 hours post-treatment .

• Chronic effects may involve gene expression changes and structural remodeling, as observed in nephropathy models .

Context-dependent signaling:

• In healthy tissue, IL-13 may serve homeostatic functions .

• In injured or diseased states, IL-13 may adopt protective roles, as seen in traumatic brain injury and EAE models .

• In other contexts, particularly with sustained overexpression, IL-13 may contribute to pathology, as in nephropathy models .

Experimental approach considerations:

• Different methods of IL-13 administration (acute treatment vs. overexpression) yield distinct outcomes .

• Local vs. systemic effects may differ substantially, explaining why localized IL-13 expression may protect against EAE while systemic overexpression induces nephropathy .

The apparent contradictions in IL-13 functions likely reflect its role as a context-dependent modulator rather than a unidirectional mediator. This complexity mirrors IL-13's diverse physiological roles and underscores the importance of considering tissue context, receptor expression, concentration, timing, and experimental approach when interpreting research findings.

What are the key takeaways about IL-13 biology in rat models for researchers?

IL-13 biology in rat models reveals several fundamental principles with significant implications for both basic research and translational applications:

Multifunctional roles beyond classical immunity:

• IL-13 functions extend well beyond its traditional classification as a Th2 cytokine .

• It acts as a neuronal signaling molecule with direct effects on synaptic function, receptor trafficking, and transcriptional regulation .

• It influences podocyte biology and glomerular filtration in the kidney .

• It modulates neuroinflammation through effects on macrophages and T cells .

Complex receptor system with distinct components:

• The IL-13 receptor system includes IL-13Rα1 (signaling-competent) and IL-13Rα2 (high-affinity binding with limited signaling) .

• These receptors demonstrate differential subcellular localization in neurons, with IL-13Rα1 predominantly postsynaptic and IL-13 predominantly presynaptic .

• The receptors exhibit complementary rather than redundant functions, suggesting evolved specialization .

Context-dependent effects:

• IL-13 can be protective in some contexts (traumatic brain injury, autoimmune encephalomyelitis) .

• It can be pathogenic in others (minimal change-like nephropathy) .

• These divergent effects likely depend on local receptor expression, concentration, duration of exposure, and tissue-specific signaling environments.

Conserved relevance to human biology:

• Many findings in rat models have been corroborated in human tissues, including neuronal expression of IL-13 and its upregulation in traumatic brain injury .

• The IL-13-induced nephropathy in rats closely resembles human minimal change nephrotic syndrome .

• These parallels highlight the translational relevance of rat model findings.

Methodological considerations:

• Appropriate controls and validations are essential, particularly when studying novel expressions or functions of IL-13 .

• Multiple complementary techniques provide more robust insights than single approaches .

• Temporal dynamics and concentration-dependence must be carefully considered when interpreting IL-13 effects .

These key principles provide a framework for designing, conducting, and interpreting IL-13 research in rat models, facilitating more nuanced understanding of this multifaceted cytokine and its potential therapeutic applications across multiple organ systems and disease states.

What critical gaps remain in our understanding of IL-13 in rat models?

Despite significant advances, several critical knowledge gaps remain in our understanding of IL-13 biology in rat models:

Cell-specific receptor signaling mechanisms:

• While IL-13Rα1 and IL-13Rα2 have been characterized , the precise signaling mechanisms in different cell types, particularly neurons, remain incompletely understood.

• The potential formation of heteroreceptor complexes with other receptors beyond IL-4R requires further investigation.

• The mechanisms by which IL-13Rα2 might modify IL-13Rα1 signaling in different cellular contexts needs clarification.

Source and regulation of IL-13 in the nervous system:

• Although neurons express IL-13 , the stimuli and mechanisms regulating its production under physiological and pathological conditions remain unclear.

• The relative contributions of neuronal versus immune-derived IL-13 in neurological disorders require further delineation.

• The transcriptional and post-transcriptional mechanisms controlling IL-13 expression in neurons need characterization.

Chronic versus acute effects:

• Most studies have focused on acute IL-13 effects or sustained overexpression .

• The consequences of physiological fluctuations in IL-13 levels over time remain poorly understood.

• Long-term adaptive responses to IL-13 signaling have not been fully characterized.

Developmental aspects:

• The ontogeny of IL-13 and its receptors during rat brain development has not been comprehensively mapped.

• The potential roles of IL-13 in neurodevelopmental processes, including synaptogenesis and circuit formation, remain to be explored.

• Age-dependent changes in IL-13 responsiveness across the lifespan represent an important area for investigation.

Sex differences:

• Given that IL-13 receptor genes map to the X chromosome , potential sex differences in IL-13 biology deserve systematic investigation.

• Sex-specific responses to IL-13 in various disease models might have significant translational implications.

Interaction with other immune mediators:

• The crosstalk between IL-13 and other cytokines or immune mediators in complex in vivo environments requires further study.

• Potential synergistic or antagonistic interactions with molecules like IL-4, IL-10, and TNF-α need characterization.