Suppression of Inflammation Delays Hair Cell Regeneration and Functional Recovery Following Lateral Line Damage in Zebrafish Larvae

Background: Human cochlear hair cells cannot spontaneously regenerate after loss. In contrast, those in fish and amphibians have a remarkable ability to regenerate after damaged. Previous studies focus on signaling mechanisms of hair cell regeneration, such as Wnt and Notch signals but seldom on the fact that the beginning of regeneration is accompanied by a large number of inflammatory responses. The detailed role of this inflammation in hair cell regeneration is still unknown. In addition, there is no appropriate behavioral method to quantitatively evaluate the functional recovery of lateral line hair cells after regeneration. Results: In this study, we found that when inflammation was suppressed, the regeneration of lateral line hair cells and the recovery of the rheotaxis of the larvae were significantly delayed. Calcium imaging showed that the function of the neuromasts in the inflammation-inhibited group was weaker than that in the non-inflammation-inhibited group at the Early Stage of regeneration, and returned to normal at the Late Stage. Calcium imaging also revealed the cause of the mismatch between the function and quantity during regeneration. Conclusions: Our results, meanwhile, suggest that suppressing inflammation delays hair cell regeneration and functional recovery when hair cells are damaged. This study may provide a new knowledge for how to promote hair cell regeneration and functional recovery in adult mammals.