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Published on: February 24, 2017
Microglia-Derived IL-6 Promotes Müller Glia Reprogramming and Proliferation in Zebrafish Retina Regeneration
Jie Xu1, Yi Li1, Xiangyu Li1
1Key Lab of Neuroregeneration of Jiangsu and Ministry of Education, Co-innovation Center of Neuroregeneration, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Nantong University, Nantong, Jiangsu Province, China.
Purpose:
Inflammation activates the Jak1-Stat3 signaling pathway in zebrafish Müller glia (MG), leading to their status transition and proliferation following retinal injury. However, the source of Stat3-activating molecules remains unclear. This study aims to explore the expression and function of a Stat3-activating cytokine IL-6 in zebrafish retina regeneration.
Methods:
Mechanical retinal injury was induced in adult zebrafish by a needle-poke lesion. Single-cell RNA sequencing (scRNAseq) and PCR were used to determine gene expression. Microglia ablation was performed by using the mpeg1:nsfb-mcherry transgenic zebrafish. Morpholino oligonucleotides, a recombinant zebrafish IL-6 protein and drugs, were used to manipulate IL-6 or Stat3 signaling in the retina. The 5-Ethynyl-2'-deoxyuridine (EdU) labeling was used to evaluate MG proliferation and the formation of MG-derived progenitor cells (MGPCs). Neuronal regeneration in the retina was analyzed by lineage tracing and immunostaining.
Results:
The scRNAseq reveals that IL-6 is mainly expressed by a subset of pro-inflammatory microglia in the injured retina. Loss- and gain-of-function experiments demonstrate that IL-6 signaling promotes MG proliferation and the formation of MGPCs following retinal injury. Additionally, IL-6 facilitates MG status transition by modulating Jak1-Stat3 signaling and the expression of regeneration-associated genes. Interestingly, IL-6 may also regulate MGPC formation via phase-dependent pro-inflammatory and anti-inflammatory mechanisms. Finally, IL-6 promotes the early differentiation of MGPCs and contributes to the regeneration of retinal neurons in the injured retina.
Conclusions:
Our study unveils the critical role of microglia-derived IL-6 in zebrafish retina regeneration, with potential implications for mammalian MG reprogramming.
Insights
Microglia-derived IL-6 drives zebrafish retinal regeneration by activating Müller glia proliferation and differentiation. This cytokine is crucial for repairing injured retinas and offers insights into mammalian Müller glia reprogramming for vision restoration.
Area of Science:
- Regenerative Medicine
- Neuroscience
- Cell Biology
Background:
- Inflammation activates the Jak1-Stat3 pathway in zebrafish Müller glia (MG), promoting their proliferation after retinal injury.
- The specific molecules activating Stat3 in this process remain unidentified.
Purpose of the Study:
- To investigate the role of the cytokine IL-6, a known Stat3 activator, in zebrafish retina regeneration.
- To explore IL-6 expression and function in the context of retinal injury and repair.
Main Methods:
- Single-cell RNA sequencing (scRNAseq) and PCR to identify gene expression patterns.
- Microglia ablation, morpholino knockdown, and recombinant IL-6 treatment to manipulate IL-6 signaling.
- EdU labeling and lineage tracing to assess Müller glia proliferation, progenitor cell formation, and neuronal regeneration.
Main Results:
- IL-6 is primarily expressed by pro-inflammatory microglia in the injured zebrafish retina.
- IL-6 signaling promotes Müller glia proliferation and the generation of Müller glia-derived progenitor cells (MGPCs).
- IL-6 modulates Jak1-Stat3 signaling, influences regeneration-associated genes, and supports early MGPC differentiation and neuronal regeneration.
Conclusions:
- Microglia-derived IL-6 is essential for zebrafish retina regeneration.
- IL-6 plays a multifaceted role, influencing Müller glia transition, proliferation, and progenitor cell differentiation.
- These findings suggest potential therapeutic strategies for mammalian retinal repair by targeting IL-6 signaling.
