Similarities and differences between IL11 and IL11RA1 knockout mice for lung fibro-inflammation, fertility and craniosynostosis
TL;DR
Ng et al. compared germline loss of il-11 with prior Il11ra1 loss-of-function phenotypes. Il11 knockout reduced TGF-β1-driven fibroblast activation and bleomycin lung fibro-inflammation, but homozygous knockout females were infertile. Unlike Il11ra1 knockout mice, Il11 knockout mice did not show craniosynostosis-like snout deformity or abnormal trabecular bone mass. A preliminary use of the authors’ earlier bleomycin protocol produced higher mortality in Il11 knockouts than in receptor knockouts, prompting a lower dose and earlier endpoint for the reported experiment. The developmental null model therefore is not a clean safety proxy for partial adult IL-11 inhibition.
Design
- CRISPR/Cas9 deleted exons 2–4 of Il11 on a C57BL/6J background, shifting the reading frame after amino acid 2 and eliminating detectable lung Il11 RNA. Knockout mice were assessed for viability, body and organ weights, hematology/chemistry, fertility, craniofacial anatomy and trabecular bone.
- Primary lung fibroblasts from 8-to-12-week-old mice were challenged for 24 h with TGF-β1 or recombinant mouse IL-11 (5 ng/ml). Imaging panels came from two independent biological experiments with 14 fields/condition; secreted collagen used n=5 and IL-11 ELISA n=3.
- Female mice aged 8–10 weeks received one 0.5-mg/kg oropharyngeal bleomycin dose and were assessed 14 days later. Histology and hydroxyproline used n=3–4/genotype for uninjured groups and n=7–10/genotype after bleomycin; lung RNA used n=4 and representative immunoblots n=3/group.
Key findings
TGF-β1-induced ACTA2, COL1A1, proliferation and collagen secretion were diminished in knockout fibroblasts, supporting a required endogenous IL-11 autocrine relay. Exogenous mouse IL-11 did not fully restore these phenotypes; the knockout cells also expressed less IL11RA, and the authors proposed both receptor reduction and loss of the feed-forward loop as explanations.
After bleomycin injury, knockout mice had less parenchymal disruption, histological fibrosis and lung hydroxyproline, with lower fibrotic/inflammatory transcripts and reduced ERK, STAT3, NF-κB and SMAD2 activation. However, preliminary use of the authors’ previously published bleomycin dose/protocol caused higher mortality in Il11 knockouts than in Il11ra1 knockouts; the reported study therefore used a lower dose and day-14 endpoint. Indexed lung weight was unchanged.
Homozygous knockout females had no detectable pregnancies or offspring in the reported crosses, while homozygous males produced viable offspring but smaller litters. The paper did not give the number of mating pairs or females tested in the main text or figure legend. Knockouts had 5–7% lower body weight at 10–12 weeks but normal tested organ-to-body-weight ratios and small-cohort hematology/chemistry panels. Craniosynostosis-like snout deformity occurred in 5/12 locally studied Il11ra1 knockouts, but Il11 knockouts did not differ from wild type (n=22 versus 23); trabecular bone measures were likewise similar (n=5–7/genotype/sex).
Extrapolation to humans
| Dimension | Status | Notes |
|---|---|---|
| Pathway conserved in humans? | partial | The paper tested mouse cells and mice; other work supports human IL-11 signaling, but this study supplied no human-cell experiment. |
| Phenotype conserved in humans? | partial | Biallelic human IL11RA loss is associated with craniosynostosis, but affected women described in the literature can reproduce, unlike female mouse nulls. |
| Replicated in humans? | no | No therapeutic IL-11 inhibition, pulmonary-fibrosis outcome or reproductive-safety study was performed in humans. gap/needs-human-replication |
Interpretation and limits
The fibrosis experiment supports the IL-11 axis as a target in this acute mouse model, while the fertility result and unexplained preliminary bleomycin mortality create material safety boundaries. Germline deletion removes signaling throughout development and implantation; it does not establish that a time-limited, partial adult antibody or RNA intervention has the same risk. Conversely, absence of overt toxicity in short adult-treatment studies cannot dismiss the pathway’s reproductive and developmental roles. The work used one inbred background, small endpoint-specific groups, no chronic drug exposure and no aging cohort. Ligand- and receptor-null phenotypes were compared across partly separate experiments rather than in one fully matched head-to-head study. Several authors were co-inventors on IL-11 therapeutic patents, and two were co-founders/shareholders of a company that developed anti-IL-11 therapeutics; the article disclosed these interests.
Relevance to the requested papers
- widjaja-2024-il11-healthspan-lifespan uses the same ligand-null line for lifespan experiments and adds late-life antibody treatment.
- wu-2026-il11-ovarian-stiffness explicitly distinguishes partial adult knockdown from complete germline pathway loss when interpreting ovarian benefit.
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