Interleukin 1 Beta prevents neovascularisation through regulation of retinal glycolysis in oxygen induced retinopathy

Abstract

Purpose : We have previously found that activation of the inflammatory cascade in mice treated with IL1β protects against retinal neovascularisation associated with oxygen induced retinopathy (OIR). We hypothesised that IL1β treatment has this effect by reducing the overall metabolic demand in the retina and thereby reducing hypoxia and its associated vascular complications.

Methods : To learn more about the mechanisms that mediate the effect of IL1β on retinal metabolism in IL1β treated mice, transcriptional profiling using RNAseq was performed on central (vaso-obliterated) and peripheral (vascularised) retinal tissue. Tissue was obtained from P14 mice undergoing OIR, treated with and without IL1β, and age-matched controls. Hypoxia was assessed by measuring vessel tortuosity and EF5 hypoxia staining at P14.

Results : VEGF mRNA was strongly upregulated in hypoxic retinas compared to normal controls. IL1β significantly reduced this VEGF upregulation (by 43%, p=0.01), which matches with the significant reduction in hypoxia demonstrated by hypoxyprobe staining. Enzymes of the glycolytic pathway were regulated in a similar fashion. The phosphofructokinase PFKP, increased during hypoxia and decreased after IL1β injection (30% reduction, p=0.01). Furthermore, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2 (PFKFB2) and PFKFB3 followed the same pattern.

Conclusions : IL1β regulates key enzymes of the glycolytic pathway in the retina. PFKP is a rate limiting enzyme for glycolysis, while the PFKFB enzymes are known to regulate PFKP in an allosteric fashion and have been shown to be important regulators of glycolysis via their regulation of phosphofructokinases. Thus, our findings strongly suggest that the retina in the OIR model responds to hypoxia with increased glycolytic activity, and that IL1β can at least partially reverse this response. We therefore hypothesise that we have identified in PFKP, PFKFB2 and PFKFB3 key regulators of retinal metabolism during OIR.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Fig.1: Intraperitoneal injection of IL1β at P12 after hypoxia reduces hypoxia at P14 in OIR. Retinal wholemounts from P14 C57BL6 mice.

 

Fig.2: Intraperitoneal injection of IL1β at P12 after hypoxia reduces hypoxia in the ischaemic central retina through manipulation of retinal metabolism. RNA sequencing performed on central retinal tissue taken from P14 C57BL6 control mice, OIR mice and OIR mice injected with IL1β IP.