IL-22 has a specialized role as a crucial bridge between the immune system and epithelial barrier tissues, regulating both tissue defense and homeostasis.

• Gene Information: IL22 encodes interleukin-22, a pro-inflammatory cytokine in the IL-10 family that functions in antimicrobial defense, tissue repair, and inflammatory responses. It acts on non-immune cells rather than immune cells, making its activity centered on epithelial tissues and barrier protection.
• Protein Expression: IL-22 is primarily produced by specialized immune cells, most notably Th17 cells, Th22 cells, and group 3 innate lymphoid cells (ILC3s). Its expression is strongly induced by IL-23 and is typically a response triggered by the presence of extracellular pathogens or tissue injury at mucosal and skin barriers.
• Signaling Pathway: IL-22 stimulation activates the JAK1 and TYK2 kinases, which subsequently leads to the phosphorylation and activation of STAT3 (and to a lesser extent, STAT1 and STAT5). This cascade induces the transcription of genes involved in producing antimicrobial peptides (AMPs), promoting cellular proliferation, and enhancing tissue repair.
• Therapeutic Inhibition: Inhibiting IL-22 signaling helps suppress abnormal tissue proliferation and inflammation in skin diseases like psoriasis. Conversely, IL-22 agonists are being developed to promote mucosal healing and tissue regeneration in conditions like inflammatory bowel disease.

IL22

• The exons 1-5 of mouse Il22 gene that encode the whole molecule (ATG to STOP codon) are replaced by human counterparts in B-hIL22/hIL22RA1/hIL10RB mice.
• The promoter, 5’UTR and 3’UTR region of the mouse gene are retained. The human IL22 expression is driven by endogenous mouse Il22 promoter, while mouse Il22 gene transcription and translation will be disrupted.

IL22RA1

• The exons 2-5 of mouse Il22ra1 gene that encode extracellular domain are replaced by human counterparts in B-hIL22/hIL22RA1/hIL10RB mice. The genomic region of mouse Il22ra1 gene that encodes transmembrane domain and cytoplasmic portion is retained.
• The promoter, 5’UTR and 3’UTR region of the mouse gene are also retained. The chimeric IL22RA1 expression is driven by endogenous mouse Il22ra1 promoter, while mouse Il22ra1 gene transcription and translation will be disrupted.

IL10RB

• The exons 2-6 of mouse Il10rb gene that encode extracellular domain and were replaced by human counterparts in B-hIL22/hIL22RA1/hIL10RB mice. The genomic region of mouse Il10rb gene that encodes signal peptide, transmembrane domain and cytoplasmic portion was retained.
• The promoter, 5’UTR and 3’UTR region of the mouse gene were also retained. The chimeric IL10RB expression was driven by endogenous mouse Il10rb promoter, while mouse Il10rb gene transcription and translation will be disrupted.

• Human IL22, IL22RA1, IL10RB mRNA was detectable only in homozygous B-hIL22/hIL22RA1/hIL10RB mice , but not in wild-type C57BL/6JNifdc mice.

Species specific analysis of IL10RB gene expression in wild-type C57BL/6JNifdc mice and homozygous humanized B-hIL22/hIL22RA1/hIL10RB mice by RT-PCR. Small intestine and splenocytes were collected from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hIL22/hIL22RA1/hIL10RB mice (H/H, H/H,H/H). Mouse Il22, Il22ra1, Il10rb mRNA was detectable only in wild-type C57BL/6JNifdc mice. Human IL22, IL22RA1, IL10RB mRNA was detectable only in homozygous B-hIL22/hIL22RA1/hIL10RB mice , but not in wild-type C57BL/6JNifdc mice. The positive band was confirmed to be correct by sequencing.

• Mouse IL22 was only detectable in wild-type C57BL/6 mice.
• Human IL22 was exclusively detectable in homozygous B-hIL22/hIL22RA1/hIL10RB mice.

Strain specific IL22 expression analysis in wild-type C57BL/6JNifdc mice and homozygous humanized B-hIL22/hIL22RA1/hIL10RB mice by ELISA. Serum was collected from wild-type C57BL/6JNifdc mice (female, n=3, 6-7-week-old) and homozygous B-hIL22/hIL22RA1/hIL10RB mice (female, n=2, 6-7-week-old) stimulated with anti-mouse CD3ε antibody (7.5 μg/mouse, i.p.) and anti-mouse CD28 antibody (5 μg/mouse, i.p.) in vivo for 3 hours. Expression level of mouse and human IL22 were analyzed by ELISA (anti-mouse IL22 antibody: Abcam, ab223857; anti-human IL22 antibody: Abcam, ab216170). Mouse IL22 was only detectable in wild-type C57BL/6 mice. Human IL22 was exclusively detectable in homozygous B-hIL22/hIL22RA1/hIL10RB mice. Values are expressed as mean ± SEM.

• Mouse IL10RB was detectable in wild-type C57BL/6JNifdc mice and homozygous B-hIL22/hIL22RA1/hIL10RB mice due to the cross-reactivity of antibodies.
• Human IL10RB was detectable in homozygous B-hIL22/hIL22RA1/hIL10RB mice.

Strain specific IL10RB expression analysis in homozygous B-hIL22/hIL22RA1/hIL10RB mice by flow cytometry. Peritoneal exudative macrophages were collected from wild-type C57BL/6JNifdc mice and homozygous B-hIL22/hIL22RA1/hIL10RB mice, protein expression was analyzed by flow cytometry with anti-mouse IL10RB antibody (R&D, FAB53681A) and anti-human IL10RB antibody (Biolegend, 396803). Mouse IL10RB was detectable in wild-type C57BL/6JNifdc mice and homozygous B-hIL22/hIL22RA1/hIL10RB mice due to the cross-reactivity of antibodies. Human IL10RB was detectable in homozygous B-hIL22/hIL22RA1/hIL10RB mice.