Role of the Btk-PLCγ2 Signaling Pathway in the Bone Destruction of Apical Periodontitis

Abstract

Chronic apical periodontitis is characterized by alveolar bone absorption in the apical region and is the result of the participation of various inflammatory mediators. Studies have shown that the Bruton tyrosine kinase- (Btk-) phospholipase Cγ2 (PLCγ2) signaling pathway plays an important role in bone absorption, but it is unknown whether it plays a role in apical periodontitis bone destruction. Therefore, this study verified the role of Btk and PLCγ2 in bone resorption of apical periodontitis by in vivo and in vitro experiments. In the in vivo experiment, a mice model of apical periodontitis was established; apical bone resorption was confirmed by the numbers of osteoclasts and HE staining. Btk, PLCγ2, and nuclear factor of activated T-cells 1 (NFATc-1) were detected by immunohistochemical staining. In the in vitro experiment, lipopolysaccharides (LPS) were used to stimulate osteoclast precursor cell RAW264.7 to establish an inflammatory microenvironment and detect osteoclast differentiation. By silencing Btk, the expression of Btk, PLCγ2, and NFATc-1 was detected by real-time qPCR and Western blot, and osteoclastogenesis was detected by enzyme histochemical staining to further confirm the role of Btk in bone resorption. It was found that the expression of Btk, PLCγ2, and NFATc-1 changed significantly with the progression of inflammation and bone destruction, indicating that Btk and PLCγ2 may be involved in the progression of inflammation in apical periodontitis and bone absorption. In vitro experiments confirmed that the differentiation of osteoclasts and the expression of PLCγ2 and NFATc-1 were significantly inhibited after silencing Btk expression, but osteoclast precursor cells could be differentiated due to the proinflammatory factor lipopolysaccharide. This study demonstrates that Btk and PLCγ2 are key factors involved in the apical inflammatory response and bone destruction.

Discovery of Novel Potent and Fast BTK PROTACs for the Treatment of Osteoclasts-Related Inflammatory Diseases

“…Osteoclasts serve as a crucial factor in alveolar bone resorption, eventually resulting in tooth loss as a symptom of periodontal diseases (PD). 50 Following the investigation of the antiosteoclastogenic effects of compound 23 in vitro, we proceeded to evaluate its activities on the ligature-induced mouse PD model. To induce PD, a LPS-soaked ligature (5−0 silk) was positioned around the right second molar on day 1 in 8-weekold male C57BL/6 mice.…”

“…Studies have demonstrated that RANKL triggers the activation of BTK, which subsequently leads to the phosphorylation of phospholipase C gamma 2 (PLCγ2). This, in turn, activates the calcium signaling pathway and NFATc1, a transcription factor that is essential for osteoclast differentiation. − To investigate the potential of compound 23 in inhibiting RANKL-induced osteoclast differentiation, we initially assessed its efficacy in decreasing the levels of BTK protein in mouse bone marrow macrophages (BMMs). Our results demonstrated that compound 23 could effectively degrade BTK protein in BMMs (Figure A,B).…”

Identification of crosstalk and immune related genes between Periodontitis and Rheumatoid Arthritis and construction of the ceRNA Network

“…And some BTK inhibition were used to treat RA by altering B cell development affecting subsequent immune processes to obtain commendable curative effect (Ringheim et al, 2021). And there are studies showed the expression levels of BTK and its downstream factors was prominent increased in osteoclasts in the apical periodontal in ammatory environment, which explored BTK may be involved in the process of osteoclast in ammation (Wang et al, 2019). Participated in activation and differentiation pathways in lymphocytes, dendritic cells and endothelial cells, CD48 is found on the surface of these immune cells.…”

Recent advances of NFATc1 in rheumatoid arthritis-related bone destruction: mechanisms and potential therapeutic targets

“…Silencing Btk resulted in a notable inhibition of osteoclast differentiation, as well as a reduction in the expression of PLCγ2 and NFATc1. These findings suggest that Btk and PLCγ2 are key factors involved in the onset of bone destruction (Wang et al 2019 ). Zhuang et al discovered that the Sema6A-plexin-A2 axis mediates NFATc1 activation via PLCγ signaling, thereby promoting osteoclast formation (Zhuang et al 2019 ).…”