Spirulina platensis components mitigate bone density loss induced by simulated microgravity: A mechanistic insight

Area of Science:

• Space biology
• Nutritional science
• Bone metabolism

Background:

• Microgravity induces bone loss, a significant concern for long-duration space missions.
• Spirulina platensis (SP) is a nutrient-rich microalga with potential anti-osteoporotic properties.
• The specific bioactive components and mechanisms of SP in mitigating bone loss are not fully understood.

Purpose of the Study:

• To investigate the effects of different Spirulina platensis (SP) components (proteins, polysaccharides, lipids, residue) on bone density and metabolism in a microgravity model.
• To elucidate the molecular mechanisms underlying SP's bone-protective effects, including key signaling pathways and gut microbiota modulation.

Main Methods:

• Utilized a hindlimb suspension (HLS) model to simulate microgravity conditions in rodents.
• Administered distinct fractions of SP: proteins (SPP), polysaccharides (SPS), lipids (SPL), and residue (SPR).
• Assessed bone mineral density, oxidative stress markers, gut microbiota composition, and key signaling pathway proteins (e.g., FoxO3, Wnt/β-catenin).

Main Results:

• SPP and SPS significantly improved bone density and reduced oxidative stress.
• SP components modulated the FoxO3/Wnt/β-catenin pathway, decreasing FoxO3a expression and increasing Wnt signaling and β-catenin, thereby promoting bone formation.
• SP administration fostered beneficial gut bacteria (e.g., Turicibacter), altered the Firmicutes-to-Bacteroidetes ratio, and increased short-chain fatty acids (SCFAs) production.

Conclusions:

• Spirulina platensis, particularly its protein and polysaccharide fractions, demonstrates significant potential in preventing and treating space-induced osteoporosis.
• The mechanisms involve direct effects on bone metabolism via the FoxO3/Wnt/β-catenin pathway and indirect effects through gut microbiota modulation.
• SP-derived nutrients represent a viable strategy for developing functional foods to support bone health during space exploration.