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Updated: Jun 27, 2025
Oxygen-Induced Retinopathy Model for Ischemic Retinal Diseases in Rodents
Published on: September 16, 2020
IC100, a humanized therapeutic monoclonal anti-ASC antibody alleviates oxygen-induced retinopathy in mice
Huijun Yuan1, Shaoyi Chen1, Matthew R Duncan1
1Department of Pediatrics/Division of Neonatology, Batchelor Children's Research Institute and Holtz Children's Hospital, University of Miami Miller School of Medicine, P. O. Box 016960, Miami, FL, 33101, USA.
Insights
Hyperoxia induces apoptosis-associated speck-like protein (ASC) formation, leading to microglial activation and retinopathy. An anti-ASC antibody (IC100) effectively reduced these effects in mouse models, suggesting potential for treating oxygen-related retinopathy.
Area of Science:
- Ophthalmology
- Immunology
- Neonatology
Background:
- Retinopathy of prematurity (ROP) and bronchopulmonary dysplasia (BPD) are common in premature infants.
- Inflammasome and microglia activation are implicated in ROP and BPD pathogenesis.
- Apoptosis-associated speck-like protein (ASC) is key to inflammasome assembly.
Purpose of the Study:
- To test if hyperoxia induces ASC speck formation, microglial activation, and retinopathy.
- To evaluate if an anti-ASC antibody (IC100) can prevent these effects.
Main Methods:
- Used mouse models of oxygen-induced retinopathy (OIR) and BPD.
- Administered IC100 via intravitreal or intraperitoneal injection.
- Assessed retinal vascularization, microglial activation, retinal structure, and function.
- Performed RNA-sequencing to analyze gene expression changes.
Main Results:
- Hyperoxia increased ASC specks and microglial activation in retinas.
- IC100 treatment reduced neovascularization and vaso-obliteration.
- IC100 improved retinal structure and function, and modulated gene expression related to angiogenesis and inflammation.
Conclusions:
- ASC plays a critical role in OIR pathogenesis.
- IC100 demonstrates efficacy in treating OIR in mice.
- Anti-ASC antibodies may be a potential therapy for oxygen-related retinopathies like ROP.
Background:
Retinopathy of prematurity (ROP), which often presents with bronchopulmonary dysplasia (BPD), is among the most common morbidities affecting extremely premature infants and is a leading cause of severe vision impairment in children worldwide. Activations of the inflammasome cascade and microglia have been implicated in playing a role in the development of both ROP and BPD. Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) is pivotal in inflammasome assembly. Utilizing mouse models of both oxygen-induced retinopathy (OIR) and BPD, this study was designed to test the hypothesis that hyperoxia induces ASC speck formation, which leads to microglial activation and retinopathy, and that inhibition of ASC speck formation by a humanized monoclonal antibody, IC100, directed against ASC, will ameliorate microglial activation and abnormal retinal vascular formation.
Methods:
We first tested ASC speck formation in the retina of ASC-citrine reporter mice expressing ASC fusion protein with a C-terminal citrine (fluorescent GFP isoform) using a BPD model that causes both lung and eye injury by exposing newborn mice to room air (RA) or 85% O2 from postnatal day (P) 1 to P14. The retinas were dissected on P14 and retinal flat mounts were used to detect vascular endothelium with AF-594-conjugated isolectin B4 (IB4) and citrine-tagged ASC specks. To assess the effects of IC100 on an OIR model, newborn ASC citrine reporter mice and wildtype mice (C57BL/6 J) were exposed to RA from P1 to P6, then 75% O2 from P7 to P11, and then to RA from P12 to P18. At P12 mice were randomized to the following groups: RA with placebo PBS (RA-PBS), O2 with PBS (O2-PBS), O2 + IC100 intravitreal injection (O2-IC100-IVT), and O2 + IC100 intraperitoneal injection (O2-IC100-IP). Retinal vascularization was evaluated by flat mount staining with IB4. Microglial activation was detected by immunofluorescence staining for allograft inflammatory factor 1 (AIF-1) and CD206. Retinal structure was analyzed on H&E-stained sections, and function was analyzed by pattern electroretinography (PERG). RNA-sequencing (RNA-seq) of the retinas was performed to determine the transcriptional effects of IC100 treatment in OIR.
Results:
ASC specks were significantly increased in the retinas by hyperoxia exposure and colocalized with the abnormal vasculature in both BPD and OIR models, and this was associated with increased microglial activation. Treatment with IC100-IVT or IC100-IP significantly reduced vaso-obliteration and intravitreal neovascularization. IC100-IVT treatment also reduced retinal microglial activation, restored retinal structure, and improved retinal function. RNA-seq showed that IC100 treatment corrected the induction of genes associated with angiogenesis, leukocyte migration, and VEGF signaling caused by O2. IC100 also corrected the suppression of genes associated with cell junction assembly, neuron projection, and neuron recognition caused by O2.
Conclusion:
These data demonstrate the crucial role of ASC in the pathogenesis of OIR and the efficacy of a humanized therapeutic anti-ASC antibody in treating OIR mice. Thus, this anti-ASC antibody may potentially be considered in diseases associated with oxygen stresses and retinopathy, such as ROP.
