Alteration of retinal vascular development by postnatal systemic Lipopolysaccharide administration: A novel model of Retinopathy of prematurity (ROP)

Abstract

 

Purpose

 

Our hypothesis is that a new model of ROP using immune challeges can be created and it may give insight into the pathogenesis of ROP and its treatment. So. we investigated the retinal pathological features in neonatal rat exposed to systemic Lipopolysaccharide(LPS) in rat.

 

Methods

 

SD rats were assigned to the experimental (NS-LPS) and control (NS-NS) groups. Intra-peritoneal injection of lipopolysaccharide (LPS) was administrated 3 times to Neonatal SD rat baby at postnatal 1day (P1), 3day (P3), 5day (P5). The retinas were whole-mounted and stain in Immunofluorescence of vessel (BS-Lectin), pericyte (NG2), Astrocyte (GFAP) on P7 and P14. Vessel development scoring and analysis measured by count vessel growth length(μm) from optic nerve to border line between vascularized and non-vascularized retina, branch point, vessel net hole per the unit area(mm2) in Confocal Microscopic Image. CD11c+, CD11b+, CD68+ cell by FACS and confocal IF staining. LPS infected apoptotic cells observed by TUNEL staining in 4% paraformaldehyde fixed paraffin section of retina tissue and Annexin V/PI staining in Retinal cells. Pro-inflammatory cytokine gene expression such as TNF-α, IL1b, IL6, IL12a, VEGF, THBS1, bcl2, caspase3, HIF1a, BDNF, PEDF measured by SYBR Green qRT-PCR.

 

Results

 

Administration of LPS postnatally, not prenatally, induced inflammation in the retina with recruitment of CD11c positive cells and increased expression of a set of inflammatory cytokine genes, TNF-alpha and IL-1beta. Postnatal LPS administration also suppressed retinal vessel development and deranged the retinal vascular structures combined with abnormal vascular tuft formation and peripheral ridge formation that resembles features of retinopathy of prematurity. Increased apoptosis in the retina and a decreased thickness of inner retina was also noted in LPS treated rats.

 

Conclusions

 

Neonatal systemic inflammation alters the normal development of retinal vessels by inducing retinal inflammation. Our model of systemic inflammation-induced alteration of retinal vascular development can be a novel experimental model of retinopathy of prematurity (ROP) and may provide insight into the pathogenesis of ROP.

 

 

Keywords: 706 retinopathy of prematurity • 557 inflammation • 637 pathology: experimental