Long-Acting FGF21 Inhibits Retinal Vascular Leakage in In Vivo and In Vitro Models

Abstract

The aim of the current study was to investigate the impact of long-acting fibroblast growth factor 21 (FGF21) on retinal vascular leakage utilizing machine learning and to clarify the mechanism underlying the protection. To assess the effect on retinal vascular leakage, C57BL/6J mice were pre-treated with long-acting FGF21 analog or vehicle (Phosphate Buffered Saline; PBS) intraperitoneally (i.p.) before induction of retinal vascular leakage with intravitreal injection of mouse (m) vascular endothelial growth factor 164 (VEGF164) or PBS control. Five hours after mVEGF164 injection, we retro-orbitally injected Fluorescein isothiocyanate (FITC) -dextran and quantified fluorescence intensity as a readout of vascular leakage, using the Image Analysis Module with a machine learning algorithm. In FGF21-or vehicle-treated primary human retinal microvascular endothelial cells (HRMECs), cell permeability was induced with human (h) VEGF165 and evaluated using FITC-dextran and trans-endothelial electrical resistance (TEER). Western blots for tight junction markers were performed. Retinal vascular leakage in vivo was reduced in the FGF21 versus vehicletreated mice. In HRMECs in vitro, FGF21 versus vehicle prevented hVEGF-induced increase in cell permeability, identified with FITC-dextran. FGF21 significantly preserved TEER compared to hVEGF. Taken together, FGF21 regulates permeability through tight junctions; in particular, FGF21 increases Claudin-1 protein levels in hVEGF-induced HRMECs. Long-acting FGF21 may help reduce retinal vascular leakage in retinal disorders and machine learning assessment can help to standardize vascular leakage quantification.

Pemafibrate Protects Against Retinal Dysfunction in a Murine Model of Diabetic Retinopathy

“…However, we do not exclude the potential contribution of local FGF21. Moreover, vascular protective effects of FGF21 on the retinal endothelial cells [ 16 ], systemic metabolic changes by pemafibrate administration, and direct protective effects of pemafibrate on the retina [ 57 ] could also be taken into consideration, which needs to be further studied.…”

“…In the retina, long-acting FGF21 (PF-05231023) was reported to decrease pathological retinal vessel proliferation and promote physiological retinal vascularization in a murine oxygen-induced retinopathy model [ 14 ] and protect against retinal neural dysfunction in a type 1 diabetic mouse model [ 15 ]. Furthermore, our previous study showed that long-acting FGF21 prevented retinal vascular leakage induced by VEGF in vitro and in vivo [ 16 ]. The administration of FGF21 has therapeutic effects on lipid and glucose metabolism in mice.…”

PPARα Agonist Oral Therapy in Diabetic Retinopathy

“…In addition, they indicated that long-acting FGF21 maintained retinal function in a streptozotocin-induced diabetic mouse model using electroretinography analyses [ 124 ]. Furthermore, we reported that long-acting FGF21 reduced retinal vascular leakage in vivo and in vitro via maintenance of claudin-1 expression [ 125 ]. In that study, we also detected expressions of FGFR1 and β-Klotho in human endothelial cells [ 125 ], which implies that the same strategy regarding the therapeutic role of FGF21 may also be applicable to humans.…”

“…Furthermore, we reported that long-acting FGF21 reduced retinal vascular leakage in vivo and in vitro via maintenance of claudin-1 expression [ 125 ]. In that study, we also detected expressions of FGFR1 and β-Klotho in human endothelial cells [ 125 ], which implies that the same strategy regarding the therapeutic role of FGF21 may also be applicable to humans. Retinal vascular leakage is seen in the early stage of DR patients [ 3 , 126 ].…”

Wnt signaling activates MFSD2A to suppress vascular endothelial transcytosis and maintain blood-retinal barrier

“…Whole-mounted retinas were imaged using confocal microscopy (LSM 880; Zeiss, Oberkochen, Germany). The fluorescence intensity of FITC-dextran was analyzed with Zeiss microscope software ZEN Intellesis to segment and quantify vascular leakage from retinal vessels based on previous protocols ( 60 ). Retinas were costained with Alexa Fluor 594–conjugated isolectin GS-IB 4 (Thermo Fisher Scientific; I21413).…”