Fibroblast-Secreted GDF11 Regulates Osteoclast Differentiation in Middle Ear Cholesteatoma through the SMAD2/3 Pathway by Targeting TGFBR1
Zhikai Wang1, Xing Wang2, Lun Dong1, Wei Wang1, Xiaoping Gao1,*
1 Department of Otorhinolaryngology Head and Neck Surgery, General Hospital of Ningxia Medical University, Yinchuan, China
2 Outpatient Department, Ningxia Minkang Hospital, Yinchuan, China
* Corresponding Author: Xiaoping Gao. Email: 
BIOCELL https://doi.org/10.32604/biocell.2026.081668
Received 06 March 2026; Accepted 16 June 2026; Published online 06 July 2026
Abstract
Objectives: Middle ear cholesteatoma (MEC) is a destructive and locally invasive disease that leads to erosion of bone structure and serious complications. This study aimed to investigate the role of GDF11 in promoting the differentiation of macrophages into osteoclasts
in vitro and elucidate the bone erosion mechanism in MEC.
Methods: The MEC dataset GSE116142 was subjected to bioinformatics analysis. The Growth Differentiation Factor 11 (GDF11) and Transforming Growth Factor Beta Receptor 1 (TGFBR1) expression levels in MEC were evaluated using immunohistochemical analysis. RAW264.7 cells were induced with different concentrations of recombinant GDF11 (rGDF11) with or without the TGFBR1 inhibitor AZ12601011.
Gdf11-overexpressing and
Gdf11 knockdown NIH-3T3 cell lines were constructed and co-cultured with RAW264.7 cells. Tartrate-resistant acid phosphatase (TRAP) staining was performed to identify TRAP-positive cells. The expression levels of GDF11, TGFBR1, and osteoclast-related markers were determined using reverse transcription-quantitative polymerase chain reaction and western blotting analyses.
Results: GDF11 and TGFBR1, which were significantly upregulated in MEC (
p < 0.05), were enriched in cytokine-cytokine receptor interaction and osteoclast differentiation. Treatment with AZ12601011 mitigated the rGDF11-induced upregulation of TRAP-positive cell number (
p < 0.01) and TGFBR1 (
p < 0.01),
Trap (
p < 0.01), and phosphorylated Mothers Against Decapentaplegic Homolog (Smad) 2/3 levels (
p < 0.01) and upregulated osteoclast-related factors (
p < 0.05). The number of TRAP
+ cells (
p < 0.01), the secretion of GDF11 (
p < 0.01), and the expression levels of Gdf11 (
p < 0.01), Tgfbr1 (
p < 0.01), and Nfatc1 (
p < 0.01) were significantly upregulated in the
Gdf11-overexpressing fibroblast/macrophage co-culture. In the co-culture system with
Gdf11 knockdown or AZ12601011 treatment, Gdf11-induced changes were mitigated (
p < 0.05).
Conclusion: GDF11 upregulation in fibroblasts enhances GDF11 secretion, promoting the differentiation of macrophages into osteoclasts. The elucidation of this intercellular communication can aid in developing therapeutic interventions for MEC-related bone erosion.
Keywords
Middle ear cholesteatoma; bone erosion; osteoclast differentiation; growth differentiation factor 11; transforming growth factor beta receptor 1; mothers against decapentaplegic homolog 2/3
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