Photoreceptor oxidative stress in hyperoxia-induced proliferative retinopathy accelerates rd8 degeneration

Abstract

To investigate the impact of photoreceptor oxidative stress on photoreceptor degeneration in mice carrying the rd8 mutation (C57BL/6N). We compared the hyperoxia-induced proliferative retinopathy (HIPR) model in two mouse strains (C57BL/6J and C57BL/6N). Pups were exposed to 75% oxygen, starting at birth and continuing for 14 days (P14). Mice were euthanized at P14, or allowed to recover in room air for one day (P15), seven days (P21), or 14 days (P28). We quantified retinal thickness and the length of residual photoreceptors not affected by rosette formation. In addition we explored differences in retinal immunostaining for NADPH oxidase 4 (NOX4), Rac1, vascular endothelium, and activated Mϋller cells. We analyzed photoreceptor oxidative stress using DCF staining in cross sections and quantified NOX4 protein levels using western blotting. C57BL/6N mice in HIPR showed increased oxidative stress, NOX4, and Rac1 in the photoreceptors at P14 and P15 compared to C57BL/6J. In addition, we observed significant progression of photoreceptor degeneration, with significantly accelerated rosette formation in C57BL/6N under HIPR, compared to their room air counterparts. Furthermore, C57BL/6N under HIPR had significantly thinner central retinas than C57BL/6J in HIPR. We did not find a difference in vascular disruption or Mϋller cell activation comparing the two strains in hyperoxia. In HIPR, the C57BL/6N strain carrying the rd8 mutation showed significantly accelerated photoreceptor degeneration, mediated via exacerbated photoreceptor oxidative stress, which we believe relates to Rac1-NOX dysregulation in the setting of Crb1 loss-of-function.

Recent advances in our understanding of the mechanisms of late lung development and bronchopulmonary dysplasia

“…This not only extends to strains (for example, C57BL/6 vs. C3H/HeN) but also to substrains (for example, C57BL/6J vs. C57BL/6N). This is not a trivial concern, since there are demonstrable differences in the response of the retina to 75% O 2 from P1 to P14 between C57BL/6J and C57BL/6N mouse pups (268). These effects are not limited to hyperoxia, since the gut metabolome and microbiome differ between C57BL/6J and C57BL/6N mice maintained on a high-fat diet, an area of interest in lung alveolarization (554).…”

Mouse genetic background impacts susceptibility to hyperoxia‐driven perturbations to lung maturation

“…A similar strain‐dependent inflammatory response had also been noted in adult mice from six and nine inbred strains exposed to hyperoxia. These concerns extend to substrains, given demonstrable differences in responses of the retina to 75% O 2 over the period P1 to P14, comparing C57BL/6J and C57BL/6N mouse pups …”

Leukemia inhibitory factor protects photoreceptor cone cells against oxidative damage through activating JAK/STAT3 signaling

“…Accumulating research has indicated that oxidative stress serves a crucial role in the pathogenesis of AMD (37). Oxidative stress is thought to be a major contributor to photoreceptor damage, which may eventually lead to a loss of vision (38). These processes are involved in the formation of ROS, and increasing evidence has demonstrated that oxidative stress-induced ROS production exceeds the limits of scavenging, which leads to an imbalance between the oxidative and antioxidant systems (39).…”