Antenatal inflammation induced by interleukin-1β causes retinal and sub-retinal vasculopathy in progeny

Abstract

Purpose : Preterm birth (PTB; < 37 weeks gestation) involving inflammation has numerous harmful effects on foetal development, but so far the underlying mechanism is unclear. With our inflammation-induced murine model of PTB, we intend to unveil the role of interleukin (IL)-1β in the developing retina and choroid.

Methods : CD-1 pregnant mice were injected in utero with IL-1β at gestation day (G)16 to cause PTB, and injections with the receptor’s antagonists Kineret (competitive inhibitor, already commercialised) and 101.10 (non-competitive inhibitor, recently developed by our lab) were performed sub-cutaneously at every 12h until birth. Eyes were collected from pups before (G16.5, 17, 17.5 and 18; obtained by C-section) and after birth (post-term days (P)1, 4 and 15) to measure the induction of pro-inflammatory genes with qPCR and of proteins with ELISA methods (N=5/gr). Then, retinal flat mounts and choroidal cryosections were stained for lectin to quantify vascular surface/density and thickness (N=5/gr). Finally, electroretinogram was performed on fully developed pups (P30) to assess retinal function (N=8/gr). Only stillborn animals have been excluded from the analyses. Ordinary one-way ANOVA with Tukey’s multiple comparison test were used to determine significance (p<0.05).

Results : Results show that an inflammatory response is generated before birth in the eye of the pup, which starts with an induction of Caspase-1 gene, closely followed with IL-1β and CXCL-16 genes, and a final increase in IL-12 gene preceding birth. Activated microglia is also observed in the retina and choroid of the pups before birth. During development, there is a delay in retinal vessels growth (78% decrease in IL-1 group v.s. sham at P1; 49% at P4; 27% at P15; SD=3%; p<0.001) and a long lasting thinning of the choroid (50% at P15; SD=5%; p<0.001). These phenotypes lead to functional alteration of the retina, as shown by decreased a- and b-wave amplitudes. Antenatal injections of 101.10 was efficient in preventing all deleterious effects induced by IL-1β observed, whereas Kineret had smaller effect.

Conclusions : To summarize, uterine inflammation engenders an inflammatory response in the foetal eye, which leads to deficient vessel growth in the retina, thinning of the choroid and retinal dysfunction. In addition, antenatal administration of 101.10 prevents these phenotypes and protects the eyes from damaging inflammation.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.