Mechanisms of mechanical force aggravating periodontitis: A review

Occlusal trauma aggravates periodontitis through the plasminogen/plasmin system

OBJECTIVES

Periodontitis is a common oral disease that is aggravated by occlusal trauma. Fibrin is a protein that participates in blood clotting and is involved in several human diseases. The deposition of fibrin in periodontal tissues can induce periodontitis, while mechanical forces may regulate the degradation of fibrin. Our study investigated how occlusal trauma aggravating periodontitis through regulating the plasminogen/plasmin system and fibrin deposition.

MATERIALS AND METHODS

This study included 84 C57BL/6 mice in which periodontitis was induced with or without occlusal trauma. Micro-computed tomography was used to assess bone resorption. Fibrin, fibrinogen, plasminogen, plasmin, tissue plasminogen activator (t-PA), and urokinase plasminogen activator (u-PA) levels were measured using Frazer-Lendrum staining, quantitative reverse transcription polymerase chain reaction, enzyme-linked immunosorbent assay, western blotting, immunofluorescence staining, and immunohistochemistry staining.

RESULTS

Occlusal trauma aggravated inflammation and bone resorption. The periodontitis group showed significant fibrin deposition. Occlusal trauma increased fibrin deposition and neutrophil aggregation. The periodontitis with occlusal trauma group had decreased fibrinogen, t-PA, and u-PA expression and plasmin and fibrin degradation product levels, as well as increased plasminogen levels.

CONCLUSION

Occlusal trauma promotes excessive fibrin deposition by suppressing the plasminogen/plasmin system, thus exacerbating periodontitis.

The Role of Mechanotransduction in Contact Inhibition of Locomotion and Proliferation

Contact inhibition (CI) represents a crucial tumor-suppressive mechanism responsible for controlling the unbridled growth of cells, thus preventing the formation of cancerous tissues. CI can be further categorized into two distinct yet interrelated components: CI of locomotion (CIL) and CI of proliferation (CIP). These two components of CI have historically been viewed as separate processes, but emerging research suggests that they may be regulated by both distinct and shared pathways. Specifically, recent studies have indicated that both CIP and CIL utilize mechanotransduction pathways, a process that involves cells sensing and responding to mechanical forces. This review article describes the role of mechanotransduction in CI, shedding light on how mechanical forces regulate CIL and CIP. Emphasis is placed on filamin A (FLNA)-mediated mechanotransduction, elucidating how FLNA senses mechanical forces and translates them into crucial biochemical signals that regulate cell locomotion and proliferation. In addition to FLNA, trans-acting factors (TAFs), which are proteins or regulatory RNAs capable of directly or indirectly binding to specific DNA sequences in distant genes to regulate gene expression, emerge as sensitive players in both the mechanotransduction and signaling pathways of CI. This article presents methods for identifying these TAF proteins and profiling the associated changes in chromatin structure, offering valuable insights into CI and other biological functions mediated by mechanotransduction. Finally, it addresses unanswered research questions in these fields and delineates their possible future directions.

Emerging roles of exosomes in oral diseases progression

Oral diseases, such as periodontitis, salivary gland diseases, and oral cancers, significantly challenge health conditions due to their detrimental effects on patient's digestive functions, pronunciation, and esthetic demands. Delayed diagnosis and non-targeted treatment profoundly influence patients' prognosis and quality of life. The exploration of innovative approaches for early detection and precise treatment represents a promising frontier in oral medicine. Exosomes, which are characterized as nanometer-sized extracellular vesicles, are secreted by virtually all types of cells. As the research continues, the complex roles of these intracellular-derived extracellular vesicles in biological processes have gradually unfolded. Exosomes have attracted attention as valuable diagnostic and therapeutic tools for their ability to transfer abundant biological cargos and their intricate involvement in multiple cellular functions. In this review, we provide an overview of the recent applications of exosomes within the field of oral diseases, focusing on inflammation-related bone diseases and oral squamous cell carcinomas. We characterize the exosome alterations and demonstrate their potential applications as biomarkers for early diagnosis, highlighting their roles as indicators in multiple oral diseases. We also summarize the promising applications of exosomes in targeted therapy and proposed future directions for the use of exosomes in clinical treatment.