PD-L1/PD-L2 deficiency alters numbers and types of microglia and transcriptomic landscape of neural retina

Abstract Background To investigate the effects of PD-1 ligands signaling pathway on microglia and transcriptomic expression and function of neural retina. Methods PD-L1/PD-L2 deficient mice were generated by Cyagen Biosciences Inc. (Suzhou, China). We performed quantitative and qualitative analyses of retinal microglia using mouse retinal western blotting and immunofluorescence experiments. The transcriptomic sequencing of neural retina was performed and analyzed by OE Biotech Co. Ltd. (Shanghai, China). The morphology of neural retina in PD-L1/PD-L2 deficient mice was evaluated using haematoxylin and eosin (HE) staining and in vivo optical coherence tomography (OCT). The visual evoked potential (VEP) test and measuring the photo negative response (PhNR) test assist in approaching changes in visual function in mice. Results PD-L1/PD-L2 deficiency decreased the total number of retinal microglia in neural retina. The activated microglia (M2 microglia) was increased in PD-L1/PD-L2 deficient mice, accompanied by increased STAT6 pathway activation. Transcriptome sequencing and analysis revealed the activation of the PI3K-Akt and MAPK signalling pathways in neural retina of PD-L1/PD-L2 knockout mice. The PD-L1/PD-L2 deficiency did not impact on the morphology and visual function of the neural retina. Conclusions PD-L1/PD-L2 deficiency alters numbers and types of microglia and transcriptomic landscape of neural retina.