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The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesis.

ABSTRACT: BACKGROUND:Age-related macular degeneration (AMD) is a multifactorial chronic disease of the eye. Several candidate pathways have been hypothesized to play a role in AMD pathogenesis. Our work and those of others suggests inflammasome activity as a mechanism associated with retinal pigment epithelial (RPE) cell demise. X-linked inhibitor of apoptosis protein (XIAP), an anti-apoptosis factor, has recently been shown to regulate inflammasome activity in non-ocular cells. The purpose of this study is to characterize XIAP's regulatory role in RPE. METHODS:Protein lysates of eye tissues from rats (vinpocetine- or aurin tricarboxylic acid complex-treated, ATAC, vs naïve) and mice (wild type vs Caspase-4-/-) were utilized to analyze XIAP protein levels. Immunohistochemistry was used to detect NLRP3 levels in the RPE layer. In vitro inflammasome activation on RPE cells was achieved with L-leucyl-L-leucine methyl ester (Leu-Leu-OMe) stimulation. Levels of XIAP mRNA and 18S RNA were quantified by RT-PCR. Cell culture supernatants were tested directly for secreted IL-1? by ELISA or concentrated for the detection of secreted IL-18 by western blot. Protein lysates from RPE in cell culture were collected for the measurement of cleaved caspase-1 p20, XIAP, and GAPDH. Data are presented as Mean?±?SD. p?

SUBMITTER: Gao J

PROVIDER: S-EPMC6706877 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesis.

Gao Jiangyuan J Cui Jing Z JZ Wang Aikun A Chen Hao Hang Rachel HHR Fong Alison A Matsubara Joanne A JA Matsubara Joanne A JA

Journal of neuroinflammation 20190822 1

<h4>Background</h4>Age-related macular degeneration (AMD) is a multifactorial chronic disease of the eye. Several candidate pathways have been hypothesized to play a role in AMD pathogenesis. Our work and those of others suggests inflammasome activity as a mechanism associated with retinal pigment epithelial (RPE) cell demise. X-linked inhibitor of apoptosis protein (XIAP), an anti-apoptosis factor, has recently been shown to regulate inflammasome activity in non-ocular cells. The purpose of thi ...[more]

PMID: 31438981

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Project description:PurposeSystemic hypertension is a risk factor of age-related macular degeneration, a disease associated with chronic retinal inflammation. The main cause of acute hypertension in the elderly is consumption of dietary salt (NaCl) resulting in increased extracellular osmolarity. The aim of the present study was to determine whether extracellular osmolarity regulates the expression of cyclooxygenase (COX) genes in cultured human retinal pigment epithelial (RPE) cells, and whether COX activity is involved in mediating the osmotic expression of key inflammatory (NLRP3 and IL1B) and angiogenic factor (VEGFA) genes.MethodsExtracellular hyperosmolarity was induced by addition of NaCl or sucrose. Gene expression was determined with real-time reverse transcription (RT)-PCR. Cytosolic interleukin-1β (IL-1β) and extracellular vascular endothelial growth factor (VEGF) levels were evaluated with enzyme-linked immunosorbent assay (ELISA).ResultsExtracellular hyperosmolarity induced a dose-dependent increase in COX2 gene expression when >10 mM NaCl was added to the culture medium, while COX1 gene expression was increased at higher doses (>50 mM of added NaCl). Extracellular hypo-osmolarity decreased COX2 gene expression. High extracellular osmolarity also induced increases in the COX2 protein level. NaCl-induced expression of COX2 was mediated by various intracellular signal transduction molecules (p38 mitogen-activated protein kinase [p38 MAPK], extracellular signal-regulated kinases 1 and 2 [ERK1/2], and phosphatidylinositol-3 kinase [PI3K]), intracellular calcium signaling involving activation of phospholipase Cγ (PLCγ) and protein kinase Cα/β (PKCα/β), and the activity of nuclear factor of activated T cell 5 (NFAT5). Inhibition of fibroblast growth factor (FGF), transforming growth factor-β (TGF-β), and interleukin-1 (IL-1) receptor activities decreased NaCl-induced COX2 gene expression. Selective inhibition of COX2 activity decreased osmotic expression of the VEGFA, IL1B, and NLRP3 genes, and blocked the NaCl-induced increase in the cytosolic IL-1β level.ConclusionsThe expression of COX2 in RPE cells is osmoresponsive, and depends on NFAT5. COX2 activity stimulates hyperosmotic expression of angiogenic (VEGFA) and inflammatory factor (IL1B and NLRP3) genes, and activation of the NLRP3 inflammasome in RPE cells.

Dataset Information

The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesis.

Publications

The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesis.

Similar Datasets

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