Lipopolysaccharides increase the resorption levels and affect zebrafish scales de novo bone formation

Zebrafish is a relevant model in skeletal research, enabling insights into bone development and regeneration. Inflammation supports tissue regeneration; however, excessive or chronic inflammation can delay the healing process and contribute to the development of skeletal disorders. Bacterial infections or LPS exposure exacerbate inflammation, hindering bone regeneration. Here, we tested the effects of LPS (1 and 10 μg/mL) as an inducer of an inflammatory response and evaluated its impact on the bone using zebrafish regenerating scales as a model. Results showed that exposure to LPS leads to an inflammatory process that affects scale regenerative ability. Exposure to LPS (10 μg/mL) led to a reduction in scale area, increased scale aspect ratio, osteoclast activity with scale demineralization, as well as overexpression of osteoclastic markers (acp5 and oc-stamp) and downregulation of the osteoblastic marker sp7. Our data suggest that zebrafish regenerating scales exposed to LPS can be further developed as an in vivo screening method to elucidate the mechanisms involved in the increased bone resorption associated with inflammatory processes, to evaluate the effects on osteoblast-osteoclast interaction in fish, and to search for novel therapeutic compounds for skeletal disorders and diseases.