Periodontal Pathogen—Derived Phosphoglycerol Dihydroceramides Attenuate Piezo1-Mediated Mechanosensing in Macrophages 2309477

Abstract Introduction Phosphoglycerol dihydroceramides (PGDHCs) produced by Porphyromonas gingivalis (Pg) are emerging virulence factors that contribute to periodontal inflammation and alveolar bone destruction. Macrophage mechanosensing mediated by Piezo1 plays a crucial role in regulating inflammatory signaling and osteoclastogenesis. However, whether bacterial lipid metabolites interfere with Piezo1-dependent mechanotransduction in macrophages remains unknown. This study examined the impact of Pg—derived PGDHC on macrophage mechanosensing and its contribution to periodontal bone loss. Methods Bone marrow—derived macrophages (BMDMs) were stimulated with wild-type Pg (Pg WT), a serine palmitoyltransferase—deficient strain lacking PGDHC (Pg SPT-null), or purified PGDHC. Piezo1 activity was assessed by Yoda1-induced Ca²+ influx. Osteoclastogenesis from BMDMs was evaluated following Piezo1 activation in the presence or absence of PGDHC. The role of non-muscle myosin IIA (MYH9) was examined using immunofluorescence, blebbistatin, and siRNA-mediated Myh9 silencing. Experimental periodontitis was induced by ligature placement with oral inoculation of Pg WT or Pg SPT-null for 14 days, and alveolar bone loss was quantified by micro-CT. Results Pg WT and purified PGDHC significantly suppressed Piezo1-mediated Ca²+ influx in macrophages, whereas Pg SPT-null and other oral bacteria had no effect. PGDHC counteracted Piezo1 activation—mediated suppression of osteoclast differentiation. PGDHC colocalized with MYH9, and both blebbistatin treatment and Myh9 silencing disrupted Piezo1-mediated Ca²+ influx. In vivo, Pg WT inoculation induced significantly greater periodontal bone loss than Pg SPT-null. Conclusion Pg-derived PGDHC impairs Piezo1-mediated mechanosensing in macrophages through MYH9-dependent cytoskeletal regulation, thereby promoting osteoclastogenesis and periodontal bone loss, and identifying PGDHC inhibition as a potential therapeutic strategy for periodontitis. Funding Source NIH grants: DE-025255, DE-027851, DE-028715, DE-029709, DE-032156, DE-032907, DE-034069, DE-034154. Topic Categories Microbial, Parasitic, and Fungal Immunology (MPF)