Abstract
Purpose :
Dysregulated vasculogenesis and vascular homeostasis are central drivers of retinal diseases, including retinopathy of prematurity (ROP) and diabetic retinopathy (DR). There is a critical need to identify alternative anti-angiogenic and anti-inflammatory targets to supplement or replace current anti-VEGF treatment strategies. An atypical mitogen-activated protein kinase (MAPK) p38 pathway is one such alternative pathway. Atypical p38 is selectively activated only in response to disease signaling, representing an under-investigated therapeutic target. The purpose of this study is to explore atypical p38 signaling in retinal and neovascular cells during ROP and DR.
Methods :
Primary human retinal endothelial cells (HREC) and primary human brain pericyte cells (HBPC) were used; cells were pretreated with the chemical p38 inhibitor SB203580 followed by G protein couple-receptor (GPCR) ligands stimulation. Levels of protein expression and RNA were established, data analysis was performed relative to p38 levels in each sample. To investigate atypical p38 signaling in the retina, we used wild-type C57BL/6 and TAB1-knockin mice (DeNicola et al 2018), harboring four-point mutations to block atypical p38 signaling. Eye tissues were collected to perform H&E staining and immunohistochemical analysis allowing the investigation of retinal vasculature under either “normal” or ROP conditions.
Results :
Our preliminary data show that GPCR ligands, known to be expressed in the human retina during ROP and DR, activate atypical p38 signaling in HREC and HBPC. Chemical and peptide inhibitors block p38 activity and reduce inflammatory cytokine production including IL6. There are currently no studies describing the specific role of atypical p38 signaling in in vivo models of ROP or DR. To address this, we have initially characterized the retinal architecture and vascularity in the WT and TAB1KI mouse. Future studies will explore inflammatory and angiogenic responses during ROP.
Conclusions :
HREC utilize an atypical p38 signaling pathway, critical for regulating inflammation and neovascular responses. Inhibition of p38 signaling blocked inflammation and we predict TAB1KI mice will display a protective response to ROP and DR. Future studies will define the specific atypical p38 signaling mechanisms in ROP and DR retinas. These studies represent a novel target to regulate vascular defects in retinal vasculopathies.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.