IFNγ regulates retinal pigment epithelial fluid transport

Abstract

The present experiments show that IFNgamma receptors are mainly localized to the basolateral membrane of human retinal pigment epithelium (RPE). Activation of these receptors in primary cultures of human fetal RPE inhibited cell proliferation and migration, decreased RPE mitochondrial membrane potential, altered transepithelial potential and resistance, and significantly increased transepithelial fluid absorption. These effects are mediated through JAK-STAT and p38 MAPK signaling pathways. Second messenger signaling through cAMP-PKA pathway- and interferon regulatory factor-1-dependent production of nitric oxide/cGMP stimulated the CFTR at the basolateral membrane and increased transepithelial fluid absorption. In vivo experiments using a rat model of retinal reattachment showed that IFNgamma applied to the anterior surface of the eye can remove extra fluid deposited in the extracellular or subretinal space between the retinal photoreceptors and RPE. Removal of this extra fluid was blocked by a combination of PKA and JAK-STAT pathway inhibitors injected into the subretinal space. These results demonstrate a protective role for IFNgamma in regulating retinal hydration across the outer blood-retinal barrier in inflammatory disease processes and provide the basis for possible therapeutic interventions.

The Retinal Pigment Epithelium Utilizes Fatty Acids for Ketogenesis

“…This is consistent with a recent study that reported that ␤-HB is a preferred substrate for glutamate synthesis in neurons (36), where glutamate acts as an important neurotransmitter and as a cofactor for glutathione and amino acid synthesis. In our experiments, we found that 13 C ␤-HB metabolism was unaffected by the presence or absence of unlabeled glucose (data not shown), suggesting that glucose metabolism pathways do not compete with ␤-HB metabolism.…”

An unexpected effect of TNF-α on F508del-CFTR maturation and function

“…Indeed, host defense and efficient mucociliary clearance is achieved by the stimulation of chloride transport and subsequent regulation of airway surface hydration. Other mediators have been reported to play a role in epithelial transport, including pro-inflammatory mediators, such as prostaglandins, leukotrienes and interferon gamma [24][25][26] as well as pro-resolution mediators 27 . In other models, such as the colon adenocarcinoma-derived cell line T84, the same treatment reduced CFTR expression and function 6 .…”

Experimental Models for Study of Retinal Pigment Epithelial Physiology and Pathophysiology

“…In previous experiments we have used these primary cultures to determine the expression, polarization and function of plasma membrane transport proteins and identify specific signaling pathways that regulate RPE function [1][2][3][4][5][6][7][8][9][10][11] These characteristics as they are accumulated provide a validation set of properties that can be applied to each cell generation. The experiments summarized below identify the proteins that determine transepithelial fluid transport and the integrity of the paracellular pathway.…”