Saliva Suppresses Osteoclastogenesis in Murine Bone Marrow Cultures

Abstract

Saliva can reach mineralized surfaces in the oral cavity; however, the relationship between saliva and bone resorption is unclear. Herein, we examined whether saliva affects the process of osteoclastogenesis in vitro. We used murine bone marrow cultures to study osteoclast formation. The addition of fresh sterile saliva eliminated the formation of multinucleated cells that stained positive for tartrate-resistant acid phosphatase (TRAP). In line with the histochemical staining, saliva substantially reduced gene expression of cathepsin K, calcitonin receptor, and TRAP. Addition of saliva led to considerably decreased gene expression of receptor activator of nuclear factor kappa-B (RANK) and, to a lesser extent, that of c-fms. The respective master regulators of osteoclastogenesis (c-fos and NFATc1) and the downstream cell fusion genes (DC-STAMP and Atp6v0d2) showed decreased expression after the addition of saliva. Among the costimulatory molecules for osteoclastogenesis, only OSCAR showed decreased expression. In contrast, CD40, CD80, and CD86-all costimulatory molecules of phagocytic cells-were increasingly expressed with saliva. The phagocytic capacity of the cells was confirmed by latex bead ingestion. Based on these in vitro results, it can be concluded that saliva suppresses osteoclastogenesis and leads to the development of a phagocytic cell phenotype.

Palatal fibroblasts reduce osteoclastogenesis in murine bone marrow cultures

“…It is not surprising that reduced osteoclastogenesis goes along with a shift toward antigen presenting cells. Similar observations were made with saliva [ 15 ], and also doxycycline and minocycline induced the expression of dendritic cell markers, CD11c and CD86, in bone marrow cells in the presence of RANKL [ 14 ]. Taken together, the data provide insights into a possible paracrine mechanism on how palatal fibroblasts can reduce osteoclastogenesis while simultaneously supporting innate immunity indicated by expression of markers of antigen presenting cells, at least in vitro.…”

“…Osteoclast-associated receptor (OSCAR) and triggering receptor expressed in myeloid cells (TREM2) are receptors that are associated with the respective adaptor molecules Fc receptor common gamma chain (FcRγ) and DNAX-activating protein 12 kDa (DAP12), respectively [ 13 ]. When the differentiation shifts towards a macrophage phenotype, the expression of CD14, a co-receptor for lipopolysaccharide signaling, and the co-stimulatory proteins CD40, CD80 and CD86, commonly expressed in antigen presenting cells such as monocytes and macrophages, rise [ 14 , 15 ].…”

Continuous combined intake of polydextrose and lactitol stimulates cecal fermentation and salivary IgA secretion in rats

“…Saliva is continuously secreted into the oral cavity by the salivary glands, covering both the oral and pharyngeal mucosa (2). Moreover, it contains many important substances, such as electrolytes, mucus, antibacterial compounds, enzymes, and growth factors, which provide lubrication and initiate food digestion (3). Among various antimicrobial agents present in the saliva, IgA antibodies play an important role in the direct neutralization of infectious Journal of Oral Science, Vol.…”

“…59, No. 4,[603][604][605][606][607][608][609][610]2017 Original Continuous combined intake of polydextrose and lactitol stimulates cecal fermentation and salivary IgA secretion in rats Yuko Yamamoto 1) , Nobuhisa Kubota 2) , Toru Takahashi 3) , Masahiro To 4) , Takashi Hayashi 2) , Tomoko Shimizu 5) , Yohei Kamata 5) , Juri Saruta 2) , and Keiichi Tsukinoki 2) pathogens and their toxins (4,5) and the establishment and maintenance of mucosal homeostasis (1). A decrease in salivary IgA concentration has been suggested as a possible causal factor in the increased susceptibility to upper respiratory tract infection (URTI) observed among population groups with low immunity status, such as children, elderly people, and athletes (6).…”

The Salivary IgA Flow Rate Is Increased by High Concentrations of Short-Chain Fatty Acids in the Cecum of Rats Ingesting Fructooligosaccharides

“…The oral cavity is one of the effector organs in the mucosal immune system and closely related to the intestinal tract [3]. This region is constantly bathed in the saliva secreted by major and minor salivary glands [4], which provides a continuous rich source of electrolytes, mucus, antibacterial compounds, and enzymes that support lubrication and initiate food digestion [5]. Saliva includes many kinds of antibacterial materials [6], including immunoglobulin A (IgA), a major effector in mucosal immunity that prevents submucosal invasion of pathogens.…”