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...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2019-08-01
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| Series: | Journal of Neuroinflammation |
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| Online Access: | http://link.springer.com/article/10.1186/s12974-019-1558-5 |
| _version_ | 1818850447784411136 |
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| author | Jiangyuan Gao Jing Z. Cui Aikun Wang Hao Hang Rachel Chen Alison Fong Joanne A. Matsubara |
| author_facet | Jiangyuan Gao Jing Z. Cui Aikun Wang Hao Hang Rachel Chen Alison Fong Joanne A. Matsubara |
| author_sort | Jiangyuan Gao |
| collection | DOAJ |
| description | 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-1β 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 < 0.05 is considered statistically significant. Results The XIAP protein level was significantly increased when the inflammasome was inhibited at the “activation” step by ATAC, but not the “priming” step, in vivo. Concomitantly, NLRP3 immunoreactivity was lower in the RPE layer of animals fed with ATAC. In mice where caspase-1 cleavage was impaired by the genetic deficiency in caspase-4, the XIAP protein level increased in eye tissues. In RPE cell culture, Leu-Leu-OMe stimulation led to caspase-1 cleavage, cytokine secretion, and XIAP reduction, which can be abolished by Z-YVAD-FMK. When XIAP siRNA was given as a pre-treatment to RPE in vitro, Leu-Leu-OMe induced IL-1β/IL-18 secretion was enhanced, whereas overexpressing XIAP reduced IL-1β secretion under inflammasome activation, both compared to controls cells. Conclusions Together, these data suggest XIAP-mediated inhibition of inflammasome activity in RPE may provide insights into the biological consequences of inflammasome activation in RPE and reveals the caspase-1/XIAP/IL-1β/IL-18 axis as a target for broader applications in AMD biology and treatment design. |
| first_indexed | 2024-12-19T06:49:17Z |
| format | Article |
| id | doaj.art-a0d01a927da1404ba5e82c201d325483 |
| institution | Directory Open Access Journal |
| issn | 1742-2094 |
| language | English |
| last_indexed | 2024-12-19T06:49:17Z |
| publishDate | 2019-08-01 |
| publisher | BMC |
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| series | Journal of Neuroinflammation |
| spelling | doaj.art-a0d01a927da1404ba5e82c201d3254832022-12-21T20:31:49ZengBMCJournal of Neuroinflammation1742-20942019-08-0116111310.1186/s12974-019-1558-5The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesisJiangyuan Gao0Jing Z. Cui1Aikun Wang2Hao Hang Rachel Chen3Alison Fong4Joanne A. Matsubara5Department of Ophthalmology and Visual Sciences, Faculty of Medicine, Eye Care Centre, University of British ColumbiaDepartment of Ophthalmology and Visual Sciences, Faculty of Medicine, Eye Care Centre, University of British ColumbiaDepartment of Ophthalmology and Visual Sciences, Faculty of Medicine, Eye Care Centre, University of British ColumbiaDepartment of Ophthalmology and Visual Sciences, Faculty of Medicine, Eye Care Centre, University of British ColumbiaDepartment of Ophthalmology and Visual Sciences, Faculty of Medicine, Eye Care Centre, University of British ColumbiaDepartment of Ophthalmology and Visual Sciences, Faculty of Medicine, Eye Care Centre, University of British ColumbiaAbstract 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-1β 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 < 0.05 is considered statistically significant. Results The XIAP protein level was significantly increased when the inflammasome was inhibited at the “activation” step by ATAC, but not the “priming” step, in vivo. Concomitantly, NLRP3 immunoreactivity was lower in the RPE layer of animals fed with ATAC. In mice where caspase-1 cleavage was impaired by the genetic deficiency in caspase-4, the XIAP protein level increased in eye tissues. In RPE cell culture, Leu-Leu-OMe stimulation led to caspase-1 cleavage, cytokine secretion, and XIAP reduction, which can be abolished by Z-YVAD-FMK. When XIAP siRNA was given as a pre-treatment to RPE in vitro, Leu-Leu-OMe induced IL-1β/IL-18 secretion was enhanced, whereas overexpressing XIAP reduced IL-1β secretion under inflammasome activation, both compared to controls cells. Conclusions Together, these data suggest XIAP-mediated inhibition of inflammasome activity in RPE may provide insights into the biological consequences of inflammasome activation in RPE and reveals the caspase-1/XIAP/IL-1β/IL-18 axis as a target for broader applications in AMD biology and treatment design.http://link.springer.com/article/10.1186/s12974-019-1558-5Age-related macular degenerationXIAPCaspase-1InflammasomePyroptosisAnd retinal pigment epithelium |
| spellingShingle | Jiangyuan Gao Jing Z. Cui Aikun Wang Hao Hang Rachel Chen Alison Fong Joanne A. Matsubara The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesis Journal of Neuroinflammation Age-related macular degeneration XIAP Caspase-1 Inflammasome Pyroptosis And retinal pigment epithelium |
| title | The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesis |
| title_full | The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesis |
| title_fullStr | The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesis |
| title_full_unstemmed | The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesis |
| title_short | The reduction of XIAP is associated with inflammasome activation in RPE: implications for AMD pathogenesis |
| title_sort | reduction of xiap is associated with inflammasome activation in rpe implications for amd pathogenesis |
| topic | Age-related macular degeneration XIAP Caspase-1 Inflammasome Pyroptosis And retinal pigment epithelium |
| url | http://link.springer.com/article/10.1186/s12974-019-1558-5 |
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