• IL31 is a cytokine associated with chronic itch, inflammatory skin disorders, and type 2 immune responses. IL31 signals through a heterodimeric receptor complex composed of IL31 receptor alpha (IL31RA) and oncostatin M receptor beta (OSMR), leading to activation of downstream JAK/STAT and inflammatory signaling pathways. Therapeutic inhibition of IL31 or IL31RA has therefore emerged as a promising strategy for treating itch-associated inflammatory disorders.
• IL31/IL31RA/OSMR humanized mice were generated by replacing the mouse Il31 gene with the human IL31 counterpart and introducing human extracellular regions of IL31RA and OSMR into endogenous mouse loci while retaining mouse intracellular signaling domains. This design enables physiological relevant expression and functional responsiveness to human IL31-targeted therapeutics.
• The model supports translational evaluation of anti-human IL31RA antibodies, itch behavior studies, inflammatory skin disease research, cytokine signaling studies, and preclinical therapeutic efficacy assessment.

Key Advantages

• Humanized IL31–IL31RA–OSMR signaling axis
• Suitable for anti-human IL31RA antibody evaluation in vivo
• Supports translational pruritus and itch biology studies
• Preserved immune homeostasis and leukocyte composition
• Applicable to atopic dermatitis and inflammatory skin disease research
• Functional validation using nemolizumab analog treatment

Validation

• Molecular Validation: Mouse Il31 and Il31ra mRNA were detectable in wild-type mice, whereas human IL31 and IL31RA mRNA were detectable in homozygous IL31/IL31RA humanized mice by RT-PCR. Human OSMR mRNA was detected in homozygous OSMR humanized mice.
• Protein Validation: Human OSMR protein was detected in homozygous OSMR humanized mice by western blot analysis, confirming successful receptor humanization.
• Immune Homeostasis Validation: Frequencies of T cells, B cells, NK cells, dendritic cells, neutrophils, macrophages, monocytes, CD4+ T cells, CD8+ T cells, and Tregs in spleen, blood, and lymph nodes remained comparable between humanized strains and wild-type C57BL/6 mice.
• Functional Validation: Anti-human IL31RA antibody treatment significantly attenuated scratching behavior in a human IL31-induced murine pruritus model, validating translational responsiveness to anti-IL31RA therapeutics.

Applications

• Anti-human IL31RA antibody evaluation
• Pruritus and itch biology research
• Atopic dermatitis studies
• Inflammatory skin disease modeling
• Cytokine signaling research
• Preclinical efficacy assessment of IL31-targeted therapeutics

IL31

• The mouse Il31 gene that encode the full-length protein was replaced by human IL31 counterpart gene sequences in IL31/IL31RA/OSMR humanized mice.

IL31RA

• The coding sequences including human IL31RA extracellular region and mouse Il31ra intracellular region were inserted into mouse IL31RA gene in IL31/IL31RA/OSMR humanized mice.

OSMR

• The coding sequences including human IL31RA extracellular region and mouse Il31ra intracellular region were inserted into mouse IL31RA gene in IL31/IL31RA/OSMR humanized mice.

Note: The mice was obtained by IL31/IL31RA humanized mice (B-hIL31/hIL31RA mice) cross breeding with OSMR humanized mice (B-hOSMR mice).

Strain specific analysis of IL31 and IL31RA gene expression in wild-type mice and homozygous IL31/IL31RA humanized mice by RT-PCR. Testis tissues were collected from wild-type C57BL/6 mice (+/+) and IL31/IL31RA humanized mice (H/H). Mouse Il31 and Il31ra mRNA were exclusively detectable in wild-type mice. Human IL31 and IL31RA mRNA were exclusively detectable in homozygous IL31/IL31RA humanized mice, but not in wild-type mice.

Strain specific analysis of OSMR mRNA and protein expression in wild-type C57BL/6 mice and OSMR humanized mice by RT-PCR and Western blot. (A) mRNA expression. Mouse Osmr mRNA was exclusively detectable in the kidney of wild-type mice (+/+). Human OSMR mRNA was exclusively detectable in homozygous OSMR humanized mice (H/H). (B) Protein expression. Kidney tissues were collected from wild-type C57BL/6 mice (+/+) and homozygous OSMR humanized mice (H/H), and analyzed by western blot with anti-OSMR antibody. The OSMR protein was detected in homozygous OSMR humanized mice. The antibody was cross-reactive between human and mouse OSMR proteins.

Analysis of leukocyte subpopulations by flow cytometry in immune organs and blood of OSM/OSMR, IL31/IL31RA/OSMR, and IL31/IL31RA/OSM/OSMR humanized mice. Splenocytes, peripheral blood, and lymph nodes were isolated from female C57BL/6, OSM/OSMR humanized mice, IL31/IL31RA/OSMR humanized mice, and IL31/IL31RA/OSM/OSMR humanized mice (female, 6 or 7-week-old, n = 3). Single live cells were gated on the CD45⁺ population and analyzed by flow cytometry as indicated. Values are expressed as mean ± SEM.

Analysis of T-cell subpopulations by flow cytometry in immune organs and blood of IL31/IL31RA/OSMR, OSM/OSMR, and IL31/IL31RA/OSM/OSMR humanized mice. Splenocytes, peripheral blood, and lymph nodes were isolated from female C57BL/6, IL31/IL31RA/OSMR humanized mice, OSM/OSMR humanized mice, and IL31/IL31RA/OSM/OSMR humanized mice (female, 6 or 7-week-old, n = 3). Single live cells were gated on the CD3⁺ T-cell population and analyzed by flow cytometry as indicated. Values are expressed as mean ± SEM.

Experimental schedule for the induction of pruritus model and in vivo efficacy of anti-human IL31RA antibody in IL31/IL31RA/OSMR humanized mice. Human IL31 was administered to the IL31/IL31RA/OSMR humanized mice (female, 12-week-old, 6 mice/group) to induce scratching behavior. Meanwhile, the mice were treated with anti-human IL31RA antibody nemolizumab analog (in house) to evaluate its in vivo efficacy.

Anti-hIL31RA antibodies attenuate scratching behavior in IL31-induced murine pruritus model using IL31/IL31RA/OSMR humanized mice. Human IL31 was administered to the IL31/IL31RA/OSMR humanized mice (female, 12-week-old, 6 mice/group) to induce the  scratching behavior. Meanwhile, the mice were treated with anti-human IL31RA antibody nemolizumab analog (in-house) or PBS. Scratching behavior was recorded on day 1 (A), day 4 (B).Summary of the mouse itching frequency in different groups shown in figure (C). As shown, IL31-treated mice show significantly increased scratching bouts. In the nemolizumab analog treatment group, blockade of IL-31 signaling with anti-hIL-31RA antibodies significantly attenuates scratching behaviors on day 4. Values are expressed as mean ± SEM. Significance was determined by two-way ANOVA. (*P <​ 0.05, **P <​ 0.01, ***P <​ 0.0001, ns: not significant); Δ Scraching bouts： Scraching bouts of Day1 or Day4 − Scraching bouts on Day-2.

What are IL31/IL31RA/OSMR humanized mice?

IL31/IL31RA/OSMR humanized mice are genetically engineered mice expressing human IL31 and humanized IL31 receptor components, enabling translational studies of itch biology and IL31-targeted therapeutics.

Why is IL31 signaling important?

IL31 signaling plays a critical role in chronic itch, atopic dermatitis, and inflammatory skin disorders through activation of IL31RA and OSMR pathways.

Can these mice be used for antibody evaluation?

Yes. IL31/IL31RA/OSMR humanized mice support in vivo evaluation of anti-human IL31RA antibodies, including nemolizumab analogs.

Are these mice suitable for pruritus models?

Yes. Human IL31-induced scratching behavior has been successfully validated in this model.

Do IL31/IL31RA/OSMR humanized mice maintain normal immune homeostasis?

Yes. Leukocyte subset frequencies in spleen, blood, and lymph nodes are comparable to wild-type C57BL/6 mice.