Mapping cell diversity and dynamics in inflammatory temporomandibular joint osteoarthritis with pain at single-cell resolution
Supawadee Jariyasakulroj, Yang Shu, Ziying Lin, Jingyi Chen, Qing Chang, Pao-Fen Ko, Jian-Fu Chen
Supawadee Jariyasakulroj, Yang Shu, Ziying Lin, Jingyi Chen, Qing Chang, Pao-Fen Ko, Jian-Fu Chen
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Research Article Cell biology Inflammation

Mapping cell diversity and dynamics in inflammatory temporomandibular joint osteoarthritis with pain at single-cell resolution

Abstract

Temporomandibular joint (TMJ) osteoarthritis with pain is a highly prevalent disorder affecting patients’ quality of life. A comprehensive understanding of cell type diversity and its dynamics in painful TMJ osteoarthritis (TMJOA) is lacking. Here, we utilized an inflammatory TMJOA mouse model via intra-articular injection of CFA. TMJOA mice exhibited cartilage remodeling, bone loss, synovitis, increased osteoarthritis (OA) score, and orofacial pain, recapitulating hallmark symptoms in patients. Single-cell transcriptomic profiling of the TMJ was performed in conjunction with mouse genetic labeling, tissue clearing, light sheet and confocal 3D imaging, multiplex RNAscope, and immunodetection. We visualized, reconstructed, and analyzed the distribution and density of nociceptive innervation of TMJ at single-axon levels. We systematically mapped the heterogeneity and anatomical position of blood endothelial cells, synovial fibroblasts, and immune cells, including Cx3cr1-positive barrier macrophages. Importantly, TMJOA mice exhibited enhanced neurovascular coupling, sublining fibroblast hyperplasia, inflammatory immune cell expansion, disrupted signaling-dependent cell-cell interaction, and a breakdown of the sandwich-like organization consisting of synovial barrier macrophages and fibroblasts. By utilizing a mouse model with combined TMJ pain history and OA, we reveal the cellular diversity, anatomical structure, and cell dynamics of the TMJ at single-cell resolution, which facilitate our understanding and potential targeting of TMJOA.

Authors

Supawadee Jariyasakulroj, Yang Shu, Ziying Lin, Jingyi Chen, Qing Chang, Pao-Fen Ko, Jian-Fu Chen

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Figure 1

TMJ OA-like defects in CFA intra-articular injection mice.

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TMJ OA-like defects in CFA intra-articular injection mice. (A) Micro-CT ...
(A) Micro-CT of live images of a sagittal view of the mandibular condyle. Scale bar: 500 μm. (B–E) Quantification analysis of microarchitecture parameters of the subchondral bone. Values represent mean ± SD, *P < 0.05, **P < 0.01, ****P < 0.0001 (n = 4 control mice, n = 6 CFA-injected mice). BV/TV, bone volume/total volume; 1/mm, 1 trabecular number per mm region. (F) H&E staining of sagittal TMJ sections. Black dashed boxes indicate the anterior and posterior synovial tissue around the condyle. Scale bar: 500 μm. (G) TMJ synovitis tissue histopathology from boxed regions in F. The TMJ of CFA-injected mice presented features of OA-like defects, including hyperplastic epithelial lining (black arrows in anterior area) and immune cellular infiltration caused by inflammation (black arrows in posterior area). Scale bar: 100 μm. (H and I) Quantification of TMJ synovitis evaluated by Synovitis Scoring System with 2 assessment criteria: synovial hyperplasia (H) and inflammatory infiltrate (I). Values represent mean ± SD. *P < 0.05 (n = 12 sections from 3 control mice, n = 18 sections from 4 CFA-injected mice). (J) Immunofluorescence staining of Cathepsin K (green) in mandibular condyles. Scale bar: 100 μm. (K) Quantification of Cathepsin K+ osteoclast cells in subchondral bone of the TMJ condylar head. Values represent mean ± SD calculated by Student’s t test. n ≥ 3 mice, *P < 0.05. (L) H&E staining of sagittal TMJ condylar cartilage part from sections in F. Arrowheads indicate uneven surface and loss of fibrous layer in the CFA group. Note the unclear borders between cartilage and subchondral bone, uneven cartilage surfaces, and decreased hypertrophic layer thickness in the CFA group. Scale bar: 100 μm. (M) Quantification of Osteoarthritis Research Society International (OARSI) score in TMJs. Data are represented as mean ± SEM calculated by Student’s t test. n ≥ 3 mice, ***P < 0.001.