Report on the Study of Inflammasome Activation Aggravating Choroidal Neovascularization

Academic Background

Age-related macular degeneration (AMD) is a common retinal disease, particularly among the elderly. AMD is divided into dry and wet types, with wet AMD characterized by choroidal neovascularization (CNV), where abnormal blood vessels grow from the choroid or inner retina into the outer retina, leading to severe vision loss. The inflammasome is a multiprotein complex involved in the regulation of various inflammatory responses, and recent studies have shown its role in the pathogenesis of AMD. However, the specific role of the inflammasome in CNV remains unclear, especially in the laser photocoagulation-induced CNV model, where research results are highly controversial. Therefore, this study aims to explore the role of inflammasome activation in CNV by introducing a new experimental model and evaluate its potential as a therapeutic target.

Source of the Paper

This paper was co-authored by Ryan D. Makin, Ivana Apicella, Roshni Dholkawala, and others, from multiple research institutions including the University of Virginia School of Medicine, University of Tsukuba, and Nagoya City University Graduate School of Medical Sciences. The paper was published online on September 24, 2024, in the journal Angiogenesis, titled “Inflammasome activation aggravates choroidal neovascularization.”

Research Process and Results

Research Process

This study introduced a new experimental model combining laser photocoagulation and subretinal injection of inflammasome agonists to explore the role of the inflammasome in CNV. The specific process is as follows:

1. Laser-induced CNV Model: A single laser photocoagulation was performed on 6- to 8-week-old C57BL/6J mice using a 532 nm laser to induce CNV.
2. Subretinal Injection of Inflammasome Agonists: Immediately after laser photocoagulation, subretinal injections were performed using reagents such as PBS, Alu RNA, B2 RNA, Alu cDNA, and oligomerized amyloid-β (1-40).
3. Genetic and Pharmacological Interventions: The effects on CNV were assessed by genetically knocking out or pharmacologically inhibiting key components of the inflammasome signaling pathway (e.g., P2RX7, NLRP3, caspase-1, caspase-11, and MyD88).
4. Immunofluorescence and Quantitative Analysis: CNV lesion volume, macrophage infiltration, and inflammasome activation were evaluated through immunofluorescence labeling and quantitative analysis.

Main Results

1. Inflammasome Agonists Exacerbate CNV: The study found that subretinal injection of inflammasome agonists such as Alu RNA, B2 RNA, Alu cDNA, and amyloid-β significantly increased the volume of laser-induced CNV lesions. For example, the volume of CNV lesions treated with Alu RNA was significantly larger than those treated with PBS.
2. Key Role of Inflammasome Signaling Pathway: Genetic knockout or pharmacological inhibition of key components of the inflammasome signaling pathway, such as P2RX7, NLRP3, caspase-1, and MyD88, significantly mitigated the exacerbating effects of inflammasome agonists on CNV. For instance, in P2RX7 knockout mice, CNV lesion volume did not significantly increase after Alu RNA treatment.
3. Role of Macrophages in CNV: The study found that inflammasome activation promoted macrophage infiltration in CNV lesions, and this process depended on the inflammasome signaling pathway. For example, in Alu RNA-treated CNV lesions, the number of macrophages significantly increased, while in NLRP3 knockout mice, macrophage infiltration did not significantly increase.
4. Neutralization of IL-1β: The study found that IL-1β neutralizing antibodies inhibited inflammasome agonist-induced macrophage chemotaxis and CNV exacerbation, indicating that IL-1β plays a key role in inflammasome-mediated CNV.

Conclusions and Significance

This study demonstrates that inflammasome activation significantly exacerbates laser-induced CNV, and this effect depends on key components of the inflammasome signaling pathway (e.g., P2RX7, NLRP3, caspase-1, and MyD88) and macrophage infiltration. Additionally, IL-1β plays a critical role in inflammasome-mediated CNV, suggesting that IL-1β may be a potential therapeutic target for CNV.

Scientific and Application Value

This study not only reveals the specific mechanisms of the inflammasome in CNV but also provides a theoretical basis for developing therapeutic strategies targeting the inflammasome. In particular, the significant effect of IL-1β neutralizing antibodies in inhibiting CNV offers new insights for treating retinal diseases such as wet AMD.

Research Highlights

1. Introduction of a New Model: This study is the first to combine laser photocoagulation with subretinal injection of inflammasome agonists, providing a new experimental model for studying the role of the inflammasome in CNV.
2. Revealing Key Signaling Pathways: Through genetic knockout and pharmacological inhibition, the study identified the key roles of P2RX7, NLRP3, caspase-1, and MyD88 in the inflammasome signaling pathway in CNV.
3. Potential Therapeutic Value of IL-1β: The study found that IL-1β neutralizing antibodies significantly inhibited CNV, suggesting its potential as a therapeutic target.

Other Valuable Information

The study also found that inflammasome activation not only exacerbates CNV but also promotes macrophage infiltration, a process dependent on IL-1β secretion. Additionally, the study explored the role of inflammasome activation in different pathological conditions, suggesting its potential role in other retinal diseases such as diabetic retinopathy.

This study provides important clues for understanding the mechanisms of the inflammasome in CNV and lays the foundation for developing therapeutic strategies targeting the inflammasome.