Early growth response 1 reduction in peripheral blood involving condylar subchondral bone loss

Abstract

Objectives To detect whether early growth response 1 (EGR1) in peripheral blood leucocytes (PBLs) indicates temporomandibular joint (TMJ) osteoarthritis (OA) lesions. Materials and Methods Egr1 mRNA expression levels in PBLs were detected in eight malocclusion patients without temporomandibular disorder (TMD) signs and 16 malocclusion patients with clinical TMD signs with (eight) or without (eight) imaging signs of TMJ OA. Twelve 6‐week‐old rats were randomized to a control group and a unilateral anterior crossbite (UAC) group and were sampled at 4 weeks. The Egr1 mRNA expression levels in PBLs and protein expression levels in different orofacial tissues were measured. Results Patients with TMD signs with/without TMJ OA diagnosis showed lower Egr1 mRNA expression levels in PBLs than patients without TMD signs. The lower Egr1 mRNA expression was also found in the PBLs of UAC rats, which were induced to exhibit early histo‐morphological signs of TMJ OA lesions. In subchondral bone of UAC rats, EGR1 protein expression was decreased, co‐localization of EGR1 with osterix or dentin matrix protein‐1 was identified, and the number of EGR1 and osterix double‐positive cells was reduced (all p < .05). Conclusion Egr1 reduction in PBLs potentially indicates subchondral bone OA lesions at an early stage.

Osteoarthritis of the Temporomandibular Joint: A Narrative Overview

“…Some authors have attempted to highlight markers that can be used to predict the development of TMJOA. Zhang et al showed that early growth response 1 (Egr1) reduction in peripheral blood leukocytes potentially indicates early-stage subchondral bone OA [ 57 ]. Reed et al hypothesized that depletion of type VI collagen may be an early biomarker for the transition from early to end stage TMJOA [ 53 ].…”

“…Various animal models exist for the study of TMJOA using surgical (such as discectomy), mechanical (such as unilateral anterior cross-bite), chemical (such as intra-articular injections of monosodium iodoacetate or complete Freund’s adjuvant), and genetic techniques (such as Cre-recombination and knockout) [ 5 , 8 , 13 , 41 , 43 , 44 , 51 ]. The most commonly used techniques were discectomy [ 11 , 43 , 45 , 53 ], unilateral anterior cross-bite [ 36 , 38 , 44 , 46 , 54 , 57 ], intra-articular injections of monosodium iodoacetate [ 26 , 37 ], complete Freund’s adjuvant [ 41 , 48 ], and genetic techniques [ 8 , 49 , 51 ]. However, no gold standard animal model exists [ 42 ].…”

“…Most studies included in this literature review used animal models [5,6,8,11,13,36,38,[40][41][42][43][44][45][46][47][48][49][50][51][52][53][54]57]. The most commonly investigated animals were mice and rats [5,8,11,13,36,38,[41][42][43][44][45][46][47][48][49][51][52][53][54]57]. One study was performed on rabbits [6].…”

PTHrP promotes subchondral bone formation in TMJ-OA

“… 21 , 22 The subchondral bone of the condyle is located under the cartilage, and stress is transmitted from the cartilage to bone buffers to maintain the stability and shape of the TMJ. 23 , 24 Abnormal bone remodelling during the development of OA results in subchondral bone mass and structure changes. 25 Bone remodelling, a process that couples bone formation due to osteoblasts and bone absorption due to osteoclasts, plays a central role in bone homeostasis in OA.…”

Identification of transcription factors and construction of a novel miRNA regulatory network in primary osteoarthritis by integrated analysis

“…EGR1 belongs to the EGR family of C2H2-type zinc-finger protein [ 30 ]. EGR1 could accelerate cartilage hyper proliferation and degeneration by regulating KLF5 expression and β -catenin signaling pathway [ 31 ]. Specificity protein 1(SP1), as a C2H2-type zinc-finger transcription factor, inhibits the proliferation of chondrocytes and promotes the apoptosis of chondrocytes by binding with miR-145 [ 32 ].…”