Mast cell activation by NGF drives the formation of trauma-induced heterotopic ossification
Tao Jiang, Xiang Ao, Xin Xiang, Jie Zhang, Jieyi Cai, Jiaming Fu, Wensheng Zhang, Zhenyu Zheng, Jun Chu, Minjun Huang, Zhongmin Zhang, Liang Wang
Tao Jiang, Xiang Ao, Xin Xiang, Jie Zhang, Jieyi Cai, Jiaming Fu, Wensheng Zhang, Zhenyu Zheng, Jun Chu, Minjun Huang, Zhongmin Zhang, Liang Wang
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Research Article Bone biology Immunology

Mast cell activation by NGF drives the formation of trauma-induced heterotopic ossification

Abstract

Soft tissue trauma can cause immune system disturbance and neuropathological invasion, resulting in heterotopic ossification (HO) due to aberrant chondrogenic differentiation of mesenchymal stem cells (MSCs). However, the molecular mechanisms behind the interaction between the immune and nervous systems in promoting HO pathogenesis are unclear. In this study, we found that mast cell–specific deletion attenuated localized tissue inflammation, with marked inhibition of HO endochondral osteogenesis. Likewise, blockage of nerve growth factor (NGF) receptor, known as tropomyosin receptor kinase A (TrkA), led to similar attenuations in tissue inflammation and HO. Moreover, while NGF/TrkA signaling did not directly affect MSCs chondrogenic differentiation, it modulated mast cell activation in traumatic soft tissue. Mechanistically, lipid A in LPS binding to TrkA enhanced NGF-induced TrkA phosphorylation, synergistically stimulating mast cells to release neurotrophin-3 (NT3), thereby promoting MSC chondrogenic differentiation in situ. Finally, analysis of single-cell datasets and human pathological specimens confirmed the important role of mast cell–mediated neuroinflammation in HO pathogenesis. In conclusion, NGF regulates mast cells in soft tissue trauma and drives HO progression via paracrine NT3. Targeted early inhibition of mast cells holds substantial promise for treating traumatic HO.

Authors

Tao Jiang, Xiang Ao, Xin Xiang, Jie Zhang, Jieyi Cai, Jiaming Fu, Wensheng Zhang, Zhenyu Zheng, Jun Chu, Minjun Huang, Zhongmin Zhang, Liang Wang

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Figure 6

Mast cell–derived NT3 is present throughout the pathogenesis of HO.

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Mast cell–derived NT3 is present throughout the pathogenesis of HO. (A) ...
(A) Volcano plot analysis of upregulated (red) and downregulated (yellow) DEGs in BMMCs treated as shown in Figure 3A from the dataset GSE64287. Expression of the Ntf3 (red box) is significantly increased (Padj < 0.05, log2FC > 2). (B) Western blotting and densitometric quantification (right) of NT3 and TrkC in BMMCs treated with PBS and LPS for 1 hour. β-Actin was used as the loading control. n = 4 biological replicates. (C–E) Representative IHC (C), IF staining images (D), and quantification (E) of NT3 of injured tendon sections in indicated group 4 weeks, 8 weeks, or 12 weeks after tenotomy. Black and yellow arrows indicate NT3+ cells. Scale bar: 5 μm. n = 5 biological replicates. (F–H) Serum NT3 levels were measured 4 weeks, 8 weeks, and 12 weeks after HO modeling in C57BL/6J and KitW-sh/W-sh mice. n = at least 3 biological replicates. (I and J) Representative IF double-staining images and quantification (right) of FCER1A+ (green)/NT3+ (red) and KIT+ (green)/NT3+ (red) cells of injured tendon sections in indicated group 12 weeks after tenotomy, with DAPI counterstaining (blue). The number of positive cells was counted. Yellow arrows indicate mast cells. Scale bar: 5 μm (left) and 1 μm (right). n = 5 biological replicates. Data are representative of 2 independent experiments (B–J). Data were shown as mean ± SD and compared with 2-tailed unpaired Student’s t test (B, E, I, and J) or 1-way ANOVA with Tukey’s multiple-comparison test (F–H).