Claudin-5 Redistribution Induced by Inflammation Leads to Anti-VEGF–Resistant Diabetic Macular Edema

Abstract

Approximately 40% of patients with diabetic macular edema (DME) are resistant to anti-vascular endothelial growth factor (VEGF) therapy (rDME). Here, we demonstrate that significant correlations between inflammatory cytokines and VEGF, as observed in naive DME, are lost in patients with rDME. VEGF overexpression in the mouse retina caused delayed inflammatory cytokine upregulation, monocyte/macrophage infiltration (CD11b 1 Ly6C 1 CCR2 1 cells), macrophage/microglia activation (CD11b 1 CD80 1 cells), and blood-retinal barrier disruption due to claudin-5 redistribution, which did not recover with VEGF blockade alone. Phosphorylated protein analysis of VEGFoverexpressed retinas revealed rho-associated coiled-coilcontaining protein kinase (ROCK) activation. Administration of ripasudil, a selective ROCK inhibitor, attenuated retinal inflammation and claudin-5 redistribution. Ripasudil also contributed to the stability of claudin-5 expression by both transcriptional enhancement and degradation suppression in inflammatory cytokine-stimulated endothelium. Notably, the anti-VEGF agent and the ROCK inhibitor were synergic in suppressing cytokine upregulation, monocyte/macrophage infiltration, macrophage/microglia activation, and claudin-5 redistribution. Furthermore, in vitro analysis confirmed that claudin-5 redistribution depends on ROCK2 but not on ROCK1. This synergistic effect was also confirmed in human rDME cases. Our results suggest that ROCKmediated claudin-5 redistribution by inflammation is a key mechanism in the anti-VEGF resistance of DME.

Single-Cell Transcriptome Profiling Reveals the Suppressive Role of Retinal Neurons in Microglia Activation Under Diabetes Mellitus

“…Such a disruption in cell-cell interaction causes neuronal apoptosis and damage to the blood-retinal barrier (BRB), which consequently increases retinal vascular permeability and vision loss ( Eshaq et al, 2017 ). Recently studies revealed that inflammatory factors associated with the pathogenesis of diabetic retinopathy ( Arima et al, 2020 ). Pro-inflammatory factors are primarily derived from microglia in the central nervous system.…”

The Neuroprotective Effect of Short Chain Fatty Acids Against Sepsis-Associated Encephalopathy in Mice

“…Butyrate attenuated proinflammatory cytokine expression in microglia in aged mice (69), which could improve neuroinflammation. CD11b is a microglial marker secreted by activated microglia (70)(71)(72). During microglial activation, the expression of CD11b, the activated marker of microglia, is increased (73).…”

Rho-Kinase Inhibitors for the Treatment of Refractory Diabetic Macular Oedema

“…Chronic hyperglycaemia is considered the leading risk factor for DR and DMO [ 2 , 9 ]. The lack of glucose regulation produces a hyperglycaemia-induced metabolic state activating and overusing alternative metabolic pathways such as the polyol-pathway, which produces intracellular stress in osmotic cells due to the accumulation of sorbitol and protein-kinase-C-diacylglycerol (PKC-DAG) pathway, which is associated with cytotoxic oedema, vascular abnormalities, and endothelial permeability.…”

“…ROCK-1 translocation and blebbing and an increased level of activated Rho in endothelial cells were also found in diabetic rat retinas producing endothelial impairment and the DMO [ 125 , 126 ]. Rat and human models have shown that under hyperglycaemic conditions and ROCK-1 activation, which occurred in the RPE, occludin, ZO-1 and claudin-5 protein levels are reduced, destabilising tight junctions in endothelial cells and causing inner-BRB disruption [ 9 , 116 ].…”

“…Furthermore, DMO persists in more than 40% of patients even after numerous intravitreal injections according to the protocol I trial [ 4 ]. The efficacy of anti-VEGF treatment may be less pronounced in the clinical practice setting where undertreatment is very frequent [ 9 , 10 , 11 ] ( Figure 1 ). Moreover, there are certain doubts about the long-term effect of the inhibition of a factor (VEGF) that is essential, among other things, to keep the choriocapillaris in good condition.…”