IL1B: A key regulatory factor in the body's immune-metabolic-neural network.

• Gene Information: Interleukin-1 beta (IL1β) is a protein-coding gene located on chromosome 2q14.1. IL1B is a member of IL-1 superfamily.
• Protein Expression: IL‑1β represents a proinflammatory cytokine secreted by activated macrophages and osteoblasts, acting as a master regulator of inflammatory cascades. This cytokine is initially translated as an inactive proprotein, which undergoes proteolytic cleavage by caspase‑1 to generate mature bioactive IL‑1β; additionally, lipopolysaccharide (LPS) robustly upregulates IL1B expression.
• Signaling Pathway: Typical IL-1β activation relies on caspase-1 cleavage following inflammasome assembly, and activated caspase-1 cleaves pro-IL-1β, pro-IL-18 and GSDMD to drive cytokine secretion and pyroptosis. Casp-8 is best known for transmitting pro-apoptotic signals downstream of death receptor signaling during extrinsic apoptosis. However, casp-8 is also able to promote both the upregulation of pro-IL-1β and its activation by direct processing at the same site targeted by casp-1.
• Therapeutic Inhibition: Although IL-1 is critical for host defense, it can also contribute to autoimmune disease via its ability to amplify T cell responses, shift the balance for immune tolerance and its direct action on non-immune cells that induces inflammation and tissue damage

IL1B

• The exons 2-7 of mouse Il1b gene that encode the entire mature IL1B domains are replaced by human counterparts in B-hIL1B mice.
• The endogenous mouse promoter, 5′ UTR, and 3′ UTR regions are retained, allowing human IL1B expression to be driven by the native mouse Il1b promoter, while endogenous mouse Il1b transcription and translation are abolished.

• Human IL1B mRNA were specifically and correctly expressed in B-hIL1B mice.

Strain specific analysis of IL1B mRNA expression in wild-type C57BL/6JNifdc mice and homozygous B-hIL1B mice by RT-PCR. Spleen RNA was isolated from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hIL1B mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human IL1B primers. Mouse Il1b mRNA was only detectable in wild-type mice. Human IL1B mRNA was exclusively detectable in homozygous B-hIL1B mice but not in wild-type mice.

• Mouse Il1b was detected on T cells populations in wild-type C57BL/6 mice.
• Human IL1B was detected on T cells populations in B-hIL1B mice, but not in wild-type C57BL/6 mice.

Strain specific IL1B expression analysis in homozygous B-hIL1B mice by ELISA. Bone marrow cell supernatant were collected from C57BL/6 (+/+) and  homozygous B-hIL1B mice (H/H) stimulated with LPS in vivo, and analyzed by ELISA with species-specific IL1B ELISA kit. Mouse IL1B was detectable in C57BL/6 mice. Human IL1B was exclusively detectable in homozygous B-hIL1B  mice but not C57BL/6 mice. ND, not detectable. Values are expressed as mean ± SEM.

• The percentages of T cells, B cells, NK cells, DCs, neutrophils, monocytes, and macrophages in homozygous B-hIL1B mice were similar to those in C57BL/6 mice.
• Humanization IL1B does not affect normal immune cell development or splenic distribution.

Analysis of leukocyte subpopulations by flow cytometry in immune organs and blood. Splenocytes, peripheral blood, and lymph nodes were isolated from female C57BL/6 and B-hIL1B mice (female, 6-week-old, n = 5). Single live cells were gated on the CD45⁺ population and analyzed by flow cytometry as indicated. Values are expressed as mean ± SEM.

• The proportions of CD4⁺ T cells, CD8⁺ T cells, and Tregs in homozygous B-hIL1B mice were comparable to those in C57BL/6 mice.
• Humanization of IL1B does not affect normal T cell development, differentiation, or splenic distribution.

Analysis of T-cell subpopulations by flow cytometry in immune organs and blood. Splenocytes, peripheral blood, and lymph nodes were isolated from female C57BL/6 and B-hIL1B mice (female, 6-week-old, n = 5). Single live cells were gated on the TCRβ⁺ T-cell population and analyzed by flow cytometry as indicated. Values are expressed as mean ± SEM.

Establishment of a MC38 model and in vivo efficacy study of an anti-human IL1B antibody. MC38 cells were implanted subcutaneously into homozygous B-hIL1B mice (female, 6 week-old, n=5). When the average tumor volume reached approximately 100 mm³, mice were randomized and subsequently administered the canakinumab analog via intraperitoneal injection.

Antitumor activity of anti-human IL1B antibody in B-hIL1B mice. (A) Anti-human IL1B antibody canakinumab analog (in house) inhibited MC38 tumor growth in B-hIL1B mice. Murine colon cancer MC38 cells were subcutaneously implanted into homozygous B-hIL1B mice (female, 6 week-old, n=5). Mice were grouped when tumor volume reached approximately 100 mm3, at which time they were treated with anti-human IL1B antibody canakinumab analog with different doses and schedules indicated in panel. (B) Body weight changes during treatment. As shown in panel A, anti-human IL1B antibody canakinumab analog was efficacious in controlling tumor growth in B-hIL1B mice, demonstrating that the B-hIL1B mice provide a powerful preclinical model for in vivo evaluation of anti-human IL1B antibodies. Values are expressed as mean ± SEM

Antitumor activity of anti-human IL1B antibodies in B-hIL1B mice. (A) Anti-human IL1B antibody inhibited MC38 tumor growth in B-hIL1B mice. Murine colon cancer MC38 cells were subcutaneously implanted into homozygous B-hIL1B mice (female, n=6). Mice were grouped on the first day, at which time they were treated with anti-human IL1B antibody. (B) Body weight changes during treatment. As shown in panel A, anti-human IL1B antibody was efficacious in controlling tumor growth in B-hIL1B mice, demonstrating that the B-hIL1B mice provide a powerful preclinical model for in vivo evaluation of anti-human IL1B antibodies. Values are expressed as mean ± SEM