Photoreceptor glucose metabolism determines normal retinal vascular growth

The neural cells and factors determining normal vascular growth are not well defined even though vision-threatening neovessel growth, a major cause of blindness in retinopathy of prematurity (ROP) (and diabetic retinopathy), is driven by delayed normal vascular growth.  We examined if hyperglycemia and low adiponectin (APN) levels delayed normal retinal vascularization, driven primarily by dysregulated photoreceptor metabolism.

One part of the experiments was to use targeted quantitative proteomics to measure the expression of proteins with selected reaction monitoring.  We measured the enzymes in glycolysis, the Krebs cycle, and several addition mitochondrial proteins.

We found that in a neonatal mouse model of postnatal hyperglycemia modeling early ROP, hyperglycemia caused photoreceptor dysfunction and delayed neurovascular maturation associated with changes in the APN pathway; recombinant mouse APN or APN receptor agonist adipoRon treatment normalized vascular growth. APN deficiency decreased retinal mitochondrial metabolic enzyme levels particularly in photoreceptors, suppressed retinal vascular development and decreased photoreceptor platelet-derived growth factor (Pdgfb). APN pathway activation reversed these effects. Blockade of mitochondrial respiration abolished adipoRon-induced Pdgfb increase in photoreceptors.  Photoreceptor-knockdown of Pdgfb delayed retinal vascular formation. Stimulation of the APN pathway might prevent hyperglycemia-associated retinal abnormalities andsuppress Phase I ROP in premature infants.