Activated microglia–induced neuroinflammatory cytokines lead to photoreceptor apoptosis in Aβ-injected mice


Age-related macular degeneration (AMD) is mainly characterized by the progressive accumulation of drusen deposits and loss of photoreceptors and retinal pigment epithelial (RPE) cells. Because amyloid β (Aβ) is the main component of drusen, Aβ-induced activated microglia most likely lead to neuroinflammation and play a critical role in the pathogenesis of AMD. However, the relationship between activated microglia–mediated neuroinflammatory cytokines and photoreceptor death has not been clarified. By subretinal injection of Aβ42 in mice, we mimicked an inflammatory milieu of AMD to better understand how activated microglia–induced neuroinflammatory cytokines lead to photoreceptor apoptosis in the AMD progression. We demonstrated that subretinal injection of Aβ42 induces microglial activation and increases inflammatory cytokine release, which gives rise to photoreceptor apoptosis in mice. Our results were verified in vitro by co-culture of Aβ42 activated primary microglia and the photoreceptor cell line 661W. We also demonstrated that the p38 mitogen-activated protein kinase (MAPK) signaling pathway was involved in Aβ42-induced microglial activation and inflammatory cytokine release. Overall, our findings indicate that activated microglia–derived neuroinflammatory cytokines could contribute to photoreceptor apoptosis under the stimulation of Aβ42. Moreover, this study may provide a potential therapeutic approach for AMD.

Key messages

  • Further explore the association between activated microglia–derived neuroinflammatory cytokine secretion and photoreceptor apoptosis under the stimulation of Aβ42.

  • Subretinal injection of Aβ42 induces the activation of microglia and increases proinflammatory cytokines IL-1β and COX-2 expression in the retina, which could give rise to the deterioration of visual function and aggravate photoreceptor apoptosis in mice.

  • Primary microglial are activated and the levels of proinflammatory cytokines are increased by Aβ42 stimulation, which could increase the apoptosis of photoreceptor cell line 661W in vitro.

  • The p38 MAPK signaling pathway is involved in microglial activation and photoreceptor apoptosis under Aβ42 treatment.

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Data availability

Jingfa Zhang and Fang Liu are guarantors of this work, who have full access to all the data in this study and take responsibility for the integrity and accuracy of the data. Data are available from the corresponding authors on reasonable request.


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We are grateful to Binxin Wu (Tongji University School of Medicine, Shanghai, China) for technical assistance.


This work was supported by the National Natural Science Foundation of China (81570852, 81870667, 81970810, 81970811), the Science and Technology Commission of Shanghai Municipality (19495800700), and the Clinical Research and Cultivation Project of Shanghai Municipal Hospital, China (SHDC12019X30).

Author information




Conception and design: Jingfa Zhang, Fang Liu, and Guo-Tong Xu.

Methodology: Jing Wu, Fanjun Shi, Qian Yang, Dandan Liu, Sichang Qu, and Haifeng Qin.

Data analysis: Jing Wu, Ge Gao, Hai Xie, Chaoyang Zhang, Jingfa Zhang, and Guo-Tong Xu.

Writing original draft preparation: Jing Wu and Jingfa Zhang.

Writing—review and editing: Fang Liu, Jingfa Zhang, and Guo-Tong Xu. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Fang Liu or Jingfa Zhang.

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All procedures involving the animal studies were approved (Permit Number: SHDSYY-2020-2938) and conducted in accordance with the guidelines of the Committee on the Ethics of Animal Experiments of Tongji University School of Medicine and adhered to the principles of the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research.

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Written informed consent for publication was obtained from all participants.

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The authors declare no competing interests.

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Wu, J., Gao, G., Shi, F. et al. Activated microglia–induced neuroinflammatory cytokines lead to photoreceptor apoptosis in Aβ-injected mice. J Mol Med (2021).

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  • Age-related macular degeneration
  • Microglia
  • Photoreceptor
  • Neuroinflammatory cytokines