D-Mannose prevents bone loss under weightlessness

Abstract

Background Astronauts undergo significant microgravity-induced bone loss during space missions, which has become one of the three major medical problems hindering human's long-term space flight. A risk-free and antiresorptive drug is urgently needed to prevent bone loss during space missions. D-mannose is a natural C-2 epimer of D-glucose and is abundant in cranberries. This study aimed to investigate the protective effects and potential mechanisms of D-mannose against bone loss under weightlessness. Methods The hind legs of tail-suspended (TS) rats were used to mimic weightlessness on Earth. Rats were administered D-mannose intragastrically. The osteoclastogenic and osteogenic capacity of D-mannose in vitro and in vivo was analyzed by micro-computed tomography, biomechanical assessment, bone histology, serum markers of bone metabolism, cell proliferation assay, quantitative polymerase chain reaction, and western blotting. RNA-seq transcriptomic analysis was performed to detect the underlying mechanisms of D-mannose in bone protection. Results The TS rats showed lower bone mineral density (BMD) and poorer bone morphological indices. D-mannose could improve BMD in TS rats. D-mannose inhibited osteoclast proliferation and fusion in vitro, without apparent effects on osteoblasts. RNA-seq transcriptomic analysis showed that D-mannose administration significantly inhibited the cell fusion molecule dendritic cell-specific transmembrane protein (DC-STAMP) and two indispensable transcription factors for osteoclast fusion (c-Fos and nuclear factor of activated T cells 1 [NFATc1]). Finally, TS rats tended to experience dysuria-related urinary tract infections (UTIs), which were suppressed by treatment with D-mannose. Conclusion D-mannose protected against bone loss and UTIs in rats under weightlessness. The bone protective effects of D-mannose were mediated by inhibiting osteoclast cell fusion. Our findings provide a potential strategy to protect against bone loss and UTIs during space missions.

Effect of Low-temperature Plasma on Polysaccharide Components of Pleurotus ostreatus Fungi

“…It can also be used as a carbohydrate nutrient to participate in immunomodulation and anti-tumor functions. Mannose has been widely used in industries such as food, medicine, cosmetics, and food additives [44]. Ribose exists in the form of glycoside in cells and furanose in mycelium, which is involved in the synthesis of vitamins and coenzymes.…”

D-mannose alleviates chronic periodontitis in rats by regulating the functions of neutrophils

“…As for bone loss, it was found that D-mannose attenuated bone loss induced by senility and estrogen de ciency in mice, which may be mediated by D-mannose-induced proliferation of Tregs and gut microbiota-dependent anti-in ammatory effects [18]. Another study showed that D-mannose protected against bone loss in rats under weightlessness, which was mediated by inhibiting osteoclast cell fusion [19]. However, whether D-mannose can alleviate periodontitis by regulating the functions of neutrophils remains unknown.…”