Anti-inflammatory and pro-regenerative effects of a monoterpene glycoside on experimental periodontitis in a rat model of diabetes

Dipyridamole Attenuates Experimental Periodontitis by Regulating M1 Macrophage Polarization via PKA/PKG Pathways

AIM

Periodontitis is a chronic inflammatory disease initiated by dysbiosis of the local microbial community. As a non-specific phosphodiesterase inhibitor, dipyridamole features anti-oxidant and anti-inflammatory properties. This study aimed to investigate the effects of dipyridamole in an experimental rat model of periodontitis.

METHODS

Thirty rats were divided randomly into three groups (n = 10): non-ligature group (NL), ligature-induced periodontitis group (L), and ligature-induced periodontitis with dipyridamole administered group (L + D). All rats were euthanized on Day 14. Alveolar bone resorption was analyzed by microcomputed tomography. The mRNA levels of Il1b, Il6, tumor necrosis factor alpha (Tnfa), and inducible nitric oxide synthase (iNos) in gingival tissue were assessed by real-time quantitative polymerase chain reaction (qRT-PCR). Inflammation level, osteoclasts, and macrophages infiltration were analyzed histologically. RAW264.7 macrophages were stimulated with Porphyromonas gingivalis lipopolysaccharide (P.g. LPS) to induce M1 polarization. Different concentration of dipyridamole (0/2/10 μM) was added simultaneously. To explore the role of PKA/PKG pathways, RAW 264.7 macrophages were pretreated with 10 μM H-89 (PKA inhibitor) or 1 μM KT-5823 (PKG inhibitor), respectively. Expression of pro-inflammatory cytokines and M1 markers were detected by qRT-PCR, ELISA, and flow cytometry.

RESULTS

Dipyridamole administration reduced alveolar bone loss, protein levels of inflammatory cytokines, and osteoclastogenesis in rats with experimental periodontitis. It also showed a tendency to decrease mRNA levels of Il1b, Il6, and Tnfa but without significant differences in gingival tissues. Moreover, the infiltration of macrophage and M1 macrophage polarization in gingival tissue of periodontitis rats were inhibited by dipyridamole administration. In addition, dipyridamole could downregulate the gene expression of Il1b and Tnfa, as well as the protein level of TNF-α, CD86, and iNOS in RAW264.7 treated with P.g. LPS. When PKA/PKG pathways were blocked, the suppression of TNF-α, CD86, and iNOS was reversed significantly.

CONCLUSION

Dipyridamole alleviated experimental periodontitis in rat models by regulating M1 polarization via activation of PKA/PKG pathways and emerges as a hopeful remedy for periodontitis.

From Basic Science to Clinical Practice: A Review of Current Periodontal/Mucogingival Regenerative Biomaterials

Periodontitis is a dysbiosis-driven inflammatory disease affecting the tooth-supporting tissues, characterized by their progressive resorption, which can ultimately lead to tooth loss. A step-wise therapeutic approach is employed for periodontitis. After an initial behavioral and non-surgical phase, intra-bony or furcation defects may be amenable to regenerative procedures. This review discusses the regenerative technologies employed for periodontal regeneration, highlighting the current limitations and future research areas. The search, performed on the MEDLINE database, has identified the available biomaterials, including biologicals (autologous platelet concentrates, hydrogels), bone grafts (pure or putty), and membranes. Biologicals and bone grafts have been critically analyzed in terms of composition, mechanism of action, and clinical applications. Although a certain degree of periodontal regeneration is predictable in intra-bony and class II furcation defects, complete defect closure is hardly achieved. Moreover, treating class III furcation defects remains challenging. The key properties required for functional regeneration are discussed, and none of the commercially available biomaterials possess all the ideal characteristics. Therefore, research is needed to promote the advancement of more effective and targeted regenerative therapies for periodontitis. Lastly, improving the design and reporting of clinical studies is suggested by strictly adhering to the Consolidated Standards of Reporting Trials (CONSORT) 2010 statement.