Hartnett, M. | bioRxiv Science

bioRxiv2022

Prenatal Carotenoid Supplementation with Lutein or Zeaxanthin Ameliorates Oxygen-Induced Retinopathy (OIR) in Bco2-/- Macular Pigment Mice

PurposePremature infants at risk of retinopathy of prematurity (ROP) miss placental transfer of carotenoids, lutein (L) and zeaxanthin (Z), during the third trimester. We previously demonstrated that prenatal L and Z supplementation raises carotenoid levels in infants at birth in the Lutein and Zeaxanthin in Pregnancy (L-ZIP) study (NCT03750968). Based on their antioxidant effects and bioavailability, we hypothesized that prenatal maternal supplementation with macular carotenoids would reduce risk of ROP. To test this hypothesis, we utilized "macular pigment mice" genetically engineered to take up L and Z into the retina in a model of oxygen-induced retinopathy (OIR). MethodsPregnant Bco2-/- mice were divided into nine experimental subgroups based on the type of supplementation (L, Z, or placebo) and on maternal supplementation start date corresponding to the three trimesters of human fetal development (E0, E11, and P1). Pups and nursing mothers were exposed to 75% O2 for 5 days (P7-12) and returned to room air for 5 days (P12-17). Pups were sacrificed at P12 and P17, and their retinas were analyzed for vaso-obliteration (VO) and intravitreal neovascularization (INV). ResultsPups of pregnant mice supplemented with L or Z had significant reductions in VO and INV areas compared to placebo. Prenatal carotenoid supplementation starting at E0 or E11 was significantly more protective against OIR than postnatal supplementation starting at P1. ConclusionPrenatal supplementation with L and Z was beneficial in a mouse OIR model. We recommend testing prenatal L and Z supplementation in future human clinical trials to prevent ROP.

biochemistry↗

bioRxiv2021

Regulation of neurogenesis and gliogenesis by the matricellular protein CCN2 in the mouse retina

Cellular communication network (CCN) 2 is an extracellular matrix protein with cell type- and context-dependent functions. Using a combination of mouse genetics and omic approaches, we show that CCN2 is expressed in early embryonic retinal progenitor cells (RPCs) and becomes restricted to fully differentiated Muller glial cells (MGCs) thereafter. Germline deletion of CCN2 in mice decreases BrdU labeling, reduces RPC pool, and impairs the competency of remaining RPCs to generate early and late born retinal cell types. Retinal hypocellularity and microphthalmia ensue. The transcriptomic changes associated with CCN2 inactivation include reduced marker and transcriptional regulator genes of retinal ganglion cells, photoreceptors and MGCs. Yap (Yes-associated protein), a singular node for transcriptional regulation of growth and differentiation genes, is also a target of CCN2 signals. In an organotypic model of ex vivo cultured embryonic retinas, CCN2 and YAP immunoreactivity signals overlap. Lentivirus-mediated YAP expression in CCN2-deficient retinal explants increases the number of differentiating Sox9-positive MGCs. Taken together, our data indicate that CCN2 controls the proliferative and differentiation potentials of RPCs ultimately endowing, a subpopulation thereof, with Muller glial cell fate. Summary statementA CCN2-YAP regulatory axis controls retinal progenitor cell growth and lineage commitment to neuronal and glial cell fates.

developmental biology↗