IL36B Antibody

What is IL36B and what is its role in the immune system?

IL36B (Interleukin-36 beta, also known as IL-1F8) is a pro-inflammatory cytokine belonging to the interleukin-1 family. In humans, the canonical protein has a reported length of 164 amino acid residues and a molecular mass of approximately 18.5 kDa . IL36B functions as an agonist that binds to the IL-1RL2/IL-36R receptor and signals through the co-receptor IL-1RAcP to activate NF-κB and MAPK signaling pathways .

Immunologically, IL36B plays crucial roles in:

• Promoting inflammatory responses in various tissues, particularly at epithelial barriers

• Enhancing dendritic cell maturation and function

• Polarizing naive CD4+ T cells toward Th1 responses

• Inhibiting regulatory T cell differentiation

• Stimulating production of pro-inflammatory cytokines and chemokines

• Facilitating neutrophil recruitment to sites of inflammation

IL36B is expressed primarily in epithelial cells, particularly keratinocytes, and is upregulated during inflammatory responses to cellular damage and infection .

How does IL36B differ from other members of the IL-36 family?

The IL-36 family consists of three agonists (IL-36α, IL-36β, and IL-36γ) and one antagonist (IL-36Ra). While all three agonists share the ability to bind to the IL-36 receptor and activate similar signaling pathways, they differ in several important aspects:

• Processing requirements: IL36B is selectively activated by cathepsin G through cleavage at residue arginine 5 (Arg5), whereas IL-36α is processed by cathepsin G or elastase at lysine 3 (Lys3) and alanine 4 (Ala4), and IL-36γ is activated by elastase or proteinase-3 via cleavage at valine 15 (Val15) .

• Potency: The effective concentration (EC50) of IL-36γ is reported to be lower than that of IL-36α and IL-36β, suggesting potential differences in signaling strength .

• Expression patterns: While there is overlap, the three IL-36 cytokines can exhibit different tissue expression patterns and may be induced by different stimuli .

• Isoforms: At least two isoforms of IL36B are known to exist, and certain antibodies may detect only the longer isoform .

Research indicates these differences may account for non-redundant biological functions, though all three cytokines use the same receptor complex .

What cellular sources produce IL36B and what stimuli induce its expression?

IL36B is primarily produced by:

• Keratinocytes and other epithelial cells

• Monocytes and macrophages

• Dendritic cells

Its expression is induced by:

• Toll-like receptor ligands (bacterial and viral PAMPs)

• Pro-inflammatory cytokines (IL-1β, TNF-α, IL-17A)

• Tissue damage signals

• Other IL-36 family cytokines (autocrine/paracrine feedback)

Interestingly, IL36B can amplify its own expression through positive feedback loops. For instance, when murine bone marrow-derived dendritic cells (BMDCs) were stimulated with IL-36β, they increased expression of IL-36α and IL-36γ, suggesting IL-36 cytokines can augment inflammatory responses by promoting not only their own expression but also that of other IL-36 family members .

What are the optimal applications for IL36B antibodies in experimental research?

IL36B antibodies are employed across multiple experimental techniques, with varying optimization requirements:

Western Blot:

• Typical dilutions range from 1:500-1:2000

• Best for detecting the secreted form (~17-18 kDa) and cellular precursor form

• In Western blot analysis of U-87 MG human glioblastoma/astrocytoma cell lines, IL-36β/IL-1F8 was detected at approximately 17 kDa under reducing conditions

Immunohistochemistry:

• Optimal dilutions typically range from 1:100-1:300 for paraffin-embedded sections

• Validated on human lung tissue

• May require antigen retrieval optimization depending on fixation method

Neutralization Assays:

• IL36B antibodies can neutralize IL-36β bioactivity in functional assays

• The neutralization dose (ND50) is typically 50-300 ng/mL in the presence of 20 ng/mL recombinant human IL-36β

• Functional neutralization can be measured by assessing the inhibition of IL-8 secretion from human pre-adipocytes stimulated with IL-36β

Flow Cytometry and ELISA applications are also possible but require specific validation and optimization for each antibody clone.

How should researchers validate the specificity of IL36B antibodies?

Thorough validation of IL36B antibodies should include multiple complementary approaches:

• Cross-reactivity testing: Confirm the antibody does not detect other IL-36 family members. Many commercial IL36B antibodies will not cross-react with IL-36A or IL-36G . Testing against recombinant proteins of all family members is advisable.

• Positive controls: Use validated positive control samples such as:

  • A549 cell lysates

  • U-87 MG human glioblastoma/astrocytoma conditioned media

  • HepG2 cells (demonstrated positive by Western blot)

• Isoform specificity: Be aware that some antibodies detect only specific isoforms. For example, certain IL36B antibodies will only detect the longer isoform of the two known variants .

• Knockout/knockdown validation: When possible, test on samples where IL36B has been knocked out or knocked down to confirm signal specificity.

• Peptide blocking: For polyclonal antibodies raised against synthetic peptides, perform peptide competition assays. The antiserum can be pre-incubated with the immunizing peptide to demonstrate specificity .

• Immunogen verification: Check whether the antibody was raised against full-length protein or a specific region. For example, one commercially available polyclonal antibody was produced against a synthesized peptide from the C-terminal region (amino acids 111-160) of human IL36B .

What are the best sample preparation techniques for detecting IL36B in different experimental settings?

Sample preparation varies significantly depending on the experimental approach:

For Western Blot:

• Use reducing conditions with Western Blot Buffer Group 1 for optimal detection

• Include protease inhibitors during lysis to prevent degradation

• For secreted IL36B, concentrate conditioned media using TCA precipitation or centrifugal filters

For Immunohistochemistry:

• Formalin-fixed paraffin-embedded (FFPE) tissues show good results at 1:100-1:300 dilutions

• Consider antigen retrieval methods (heat-induced or enzymatic) to expose epitopes masked during fixation

• Use positive control tissues like human lung to establish staining protocols

For Functional Assays:

• When using IL36B antibodies for neutralization, pre-incubate the antibody with recombinant IL36B before adding to cells

• In cell-based assays, include appropriate negative controls (isotype control antibodies)

• For IL-8 secretion assays, use human pre-adipocytes as responder cells

For Gene Expression Analysis:

• When studying IL36B at the transcript level, TaqMan PCR has been successfully employed

• All real-time PCRs can be run on systems like the 7900HT Sequence Detection System

• Running samples in triplicates and calculating fold change using the comparative Ct method (2^-ΔΔCt) is recommended

How do post-translational modifications affect IL36B function and antibody recognition?

IL36B requires post-translational processing to unleash its full pro-inflammatory activity, which has significant implications for both its biological function and antibody detection:

Processing Mechanisms:

• IL36B is selectively activated by cathepsin G through cleavage at residue arginine 5 (Arg5)

• The full-length protein has limited activity compared to the processed form

• Unlike IL-1β, which is processed by caspase-1, IL36B processing occurs primarily through neutrophil-derived proteases released during degranulation

Impact on Biological Activity:

• Truncated IL36B shows significantly enhanced receptor activation compared to full-length protein

• Processing represents a key regulatory checkpoint for IL36B activity in vivo

• The activating cleavage converts IL36B from a low-activity precursor to a potent pro-inflammatory mediator

Antibody Recognition Considerations:

• Antibodies raised against different epitopes may have varying abilities to recognize processed versus unprocessed forms

• N-terminal antibodies may lose reactivity after proteolytic processing

• For functional studies, researchers should consider whether their antibody recognizes the biologically active form

Experimental Design Implications:

• When studying IL36B in neutrophil-rich environments, consider the impact of processing on detection

• For neutralization studies, antibodies targeting conserved epitopes present in both processed and unprocessed forms may be more effective

• When measuring IL36B protein levels in biological samples, be aware that standard immunoassays may not distinguish between active and inactive forms

What is the current understanding of IL36B's role in the crosstalk between innate and adaptive immunity?

IL36B serves as a critical mediator in the immune system's innate-adaptive interface:

Effects on Dendritic Cells:

• IL36B stimulation of murine dendritic cells upregulates activation markers including CD80, CD86, and MHCII

• In murine monocyte-derived dendritic cells (MDDCs), IL36B induces production of IL-12p70, IL-23, and IL-10

• These changes enhance DC capacity to activate and polarize T cells

T Cell Differentiation and Function:

• IL36B potently drives Th1 responses when CD4+ T cells are stimulated under Th1 polarizing conditions

• IL36B inhibits regulatory T cell (Treg) differentiation through MyD88 and NF-κB dependent pathways

• The cytokine enhances IL-18 and IL-12p70 production in MDDCs, suggesting promotion of a Th1 phenotype

Integration with Other Inflammatory Signals:

• IL36B synergizes with IL-22 to induce IL-17A and TNF expression in human keratinocytes

• IL36B works cooperatively with IL-17A and TNF-α to increase expression of IL-6, IL-8, and TNF-α in primary human keratinocytes

• This synergy creates amplification loops between innate and adaptive immune signals

Transcriptional Programs:

• In keratinocytes, IL36B upregulates expression of IL-17A signaling-related genes (IL36G, S100A7, LCN2), p38-MAPK signaling genes (IRAK2, PLA2G4D), and genes involved in leukocyte migration

• IL36B induces IκBζ expression in human skin epidermal keratinocytes, which regulates downstream genes involved in inflammatory signaling, neutrophil chemotaxis, and leukocyte activation

This multifaceted role positions IL36B as a bridge between initial innate responses and sustained adaptive immunity, particularly at epithelial barriers.

How is IL36B involved in host defense against bacterial and viral infections?

IL36B contributes to antimicrobial defense through multiple mechanisms:

Bacterial Defense:

• The IL-36 pathway plays a protective role in polymicrobial sepsis models, with IL-36R deletion resulting in increased organ injury, mortality, and decreased bacterial clearance

• IL36B promotes macrophage polarization toward the antimicrobial M1 phenotype

• In response to bacterial components like flagellin, epithelial cells produce IL-36 cytokines, including IL36B

• IL-36 signaling in macrophages may help restrict Mycobacterium tuberculosis infection by upregulating antimicrobial peptides like cathelicidin and beta defensin 2, though in vivo studies with IL-36R-deficient mice showed no effect on Mtb infection

Viral Defense:

• During influenza virus infection, significant increases in IL-36 cytokine expression occur, with neutrophils being a major source

• The antiviral response promoted by IL-36 signaling has been leveraged in vaccine development, with truncated IL-36γ serving as an effective adjuvant in a Zika DNA vaccine

• IL-36 enhances IFN signaling by increasing expression of IFN receptor components (IFNGR1, IFNGR2, and IFNAR2) in human primary epidermal keratinocytes

Fungal Response:

• During Candida albicans infection, IL-36 production by human oral epithelial cells depends on p38, NF-κB, and PI3K signaling pathways

• Candidalysin, a PAMP expressed by C. albicans, triggers PI3K-dependent expression of IL-36 cytokines, leading to downstream production of IL-23

Regulation of Antimicrobial Responses:

• IL36B induces neutrophil recruitment through upregulation of chemokines like CXCL1 and IL-8

• Excessive IL-36 signaling can lead to immunopathology through overamplification of inflammatory responses during infection

These findings highlight IL36B's importance in orchestrating host defense while maintaining balanced immune responses to prevent tissue damage.

What is the evidence for IL36B's role in inflammatory skin diseases?

IL36B has been implicated in several inflammatory skin conditions, most notably pustular psoriasis:

Generalized Pustular Psoriasis (GPP):

• Mutations in IL36RN, which encodes the IL-36 receptor antagonist (IL-36Ra), lead to deficient regulation of IL-36 signaling including IL36B

• This dysregulation is associated with a severe form of pustular psoriasis known as DITRA (Deficiency of IL-36 Receptor Antagonist)

• Skin biopsies from patients with pustular psoriasis show upregulated IL36B expression

Therapeutic Targeting of the IL-36 Pathway:

• Spesolimab, an anti-IL-36 receptor monoclonal antibody, has shown efficacy in treating GPP

• In clinical trials, a single intravenous infusion of spesolimab resulted in 54% of patients achieving a pustulation subscore of 0 at week 1, compared to only 6% in the placebo group (p<0.001)

• RNA sequencing of skin biopsies revealed downregulation of IL-36 signaling within one week of spesolimab treatment

Cellular Mechanisms:

• IL36B triggers keratinocyte expression of inflammatory cytokines and chemokines including IL-8, CXCL-1, and CCL-20

• It synergizes with IL-22 to induce IL-17A and TNF expression in human keratinocytes

• In combination with IL-17A and TNF-α, IL36B amplifies the production of IL-6, IL-8, and TNF-α in primary human keratinocytes

• IL36B activates the transcription factor IκBζ in keratinocytes, which regulates genes involved in neutrophil chemotaxis and leukocyte activation

Experimental Models:

• In IL-36α knockout mice, there is reduced neutrophil recruitment to the epidermis and dermis, along with decreased CXCL1 generation

• Similar mechanisms likely apply to IL36B, supporting its role in neutrophilic skin inflammation

How is IL36B involved in cancer progression or suppression?

Research indicates IL36B has complex and sometimes contradictory roles in cancer:

Anti-Tumorigenic Effects:

• IL-36 cytokines can display protective functions through promotion of anti-tumorigenic inflammatory immune responses

• In colorectal cancer models, IL-36α overexpression resulted in reduced tumor weight and volume, decreased lung metastasis, and increased CD8+ T cell infiltration

• Similar mechanisms may apply to IL36B, though it has been less extensively studied than IL-36α or IL-36γ in this context

Pro-Tumorigenic Effects:

• Some studies suggest IL36B may have pro-tumorigenic effects in certain contexts

• The inflammatory environment created by IL-36 signaling might promote tumor growth in specific cancer types

• The relative contribution of IL36B to either tumor progression or anti-tumor immunity varies across different cancer types and models

Immune Cell Modulation in Tumors:

• IL36B can enhance dendritic cell maturation and function, potentially improving anti-tumor immunity

• By promoting Th1 polarization and inhibiting regulatory T cells, IL36B may counteract immunosuppressive tumor microenvironments

• The cytokine's ability to stimulate pro-inflammatory M1 macrophage activation may contribute to anti-tumor responses

Research Challenges:

• Many studies have utilized murine models with tumors engineered to overexpress IL-36 cytokines, which may not fully recapitulate physiological conditions

• The review by Nature notes: "As none of these models fully recapitulates the true in vivo situation, the relative contribution of each of these cytokines to either drive tumor progression or facilitate the anti-tumour immune response, particularly in human cancers and in the different cancer types, remains to be fully determined"

The dual nature of IL36B's role in cancer highlights the need for context-specific analysis and consideration of the broader immune environment.

What methodological approaches are used to study IL36B in disease models?

Researchers employ diverse methodological approaches to investigate IL36B in disease contexts:

Gene Expression Analysis:

• TaqMan PCR assays are used to quantify IL36B expression in lesional skin biopsies and other tissues

• All real-time PCRs can be run on systems like the 7900HT Sequence Detection System (SDS)

• Samples are typically run in triplicates, with raw cycle threshold (Ct) values calculated using SDS software

• Fold change calculations employ the comparative Ct method (2^-ΔΔCt)

Protein Detection in Clinical Samples:

• Western blot analysis using anti-IL36B antibodies at dilutions of 1:500-1:2000

• Immunohistochemistry of paraffin-embedded tissues at 1:100-1:300 dilutions

• ELISA assays for quantitative measurement in serum or tissue lysates

Functional Assays:

• Neutralization assays measuring inhibition of IL-8 secretion from human pre-adipocytes stimulated with recombinant IL36B

• The neutralization dose (ND50) typically ranges from 50-300 ng/mL in the presence of 20 ng/mL recombinant human IL36B

Genetic Approaches:

• IL36B knockout mice to assess its role in disease development

• IL-36R knockout models to study the broader IL-36 signaling pathway

• Analysis of IL36RN mutations in patients with generalized pustular psoriasis

Therapeutic Intervention Studies:

• Clinical trials with spesolimab (anti-IL-36R antibody) for pustular psoriasis

• Assessment of treatment responses using established clinical scores like GPPGA (Generalized Pustular Psoriasis Physician Global Assessment)

• Skin biopsies for RNA sequencing to evaluate changes in IL-36 signaling pathways following treatment

Molecular Interaction Studies:

• Recombinant protein binding assays to study IL36B interactions with its receptor

• Cell-based reporter assays to monitor IL36B-induced signal transduction

• NF-κB reporter gene assays in cells expressing endogenous IL-36R

These methodological approaches provide complementary data that collectively advance our understanding of IL36B's role in disease pathogenesis and potential therapeutic applications.

What are the emerging therapeutic approaches targeting IL36B or its receptor?

Several therapeutic strategies targeting the IL-36 pathway are under investigation:

Direct Receptor Targeting:

• Spesolimab: A novel anti-IL-36 receptor monoclonal antibody that has demonstrated efficacy in generalized pustular psoriasis (GPP)

• In the Effisayil 1 trial, 54% of patients receiving spesolimab achieved a pustulation subscore of 0 at week 1, compared to only 6% in the placebo group (p<0.001)

• Spesolimab has also been evaluated in atopic dermatitis (phase IIa study), with the primary endpoint being percentage change from baseline in Eczema Area and Severity Index (EASI) score at Week 16

Mechanism of Action:

• These antibodies prevent IL-36 cytokines (including IL36B) from binding to the IL-36 receptor

• This blocks downstream signaling through NF-κB and MAPK pathways

• RNA sequencing from clinical trials revealed downregulation of IL-36 signaling signatures (including IL-17 related pathways) within one week of treatment

Patient Selection and Response Prediction:

• IL36RN mutation status has been examined as a potential predictor of response to IL-36 pathway inhibition

• Interestingly, patients responded to spesolimab regardless of IL36RN mutation status in clinical studies

• This suggests the therapeutic benefit of blocking this pathway extends beyond patients with genetic defects in IL-36Ra

Combination Approaches:

• Given the synergy between IL-36 and other inflammatory pathways (IL-17, TNF), combination therapies are being explored

• Targeting multiple inflammatory pathways simultaneously may provide enhanced efficacy in severe inflammatory diseases

Emerging Applications:

• Beyond GPP and atopic dermatitis, IL-36 pathway inhibition is being investigated in:

  • Inflammatory bowel disease

  • Rheumatoid arthritis

  • Systemic lupus erythematosus

  • Other IL-36-driven inflammatory conditions