advertisement
Abstract #71589 Published in IGR 18-3
The P2X7 receptor links mechanical strain to cytokine IL-6 upregulation and release in neurons and astrocytes
Lu W; Albalawi F; Beckel JM; Lim JC; Laties AM; Mitchell CHJournal of Neurochemistry 2017; 0:
BACKGROUND: Mechanical strain in neural tissues can lead to the upregulation and release of multiple cytokines including IL-6. In the retina, the mechanosensitive release of ATP can autostimulate P2X7 receptors on both retinal ganglion cell neurons and optic nerve head astrocytes. Here we asked whether the purinergic signaling contributed to the IL-6 response to increased intraocular pressure (IOP) in vivo, and stretch or swelling in vitro. METHODS: Rat and mouse eyes were exposed to non-ischemic elevations in IOP to 50-60 mmHg for 4 hrs. A PCR array was used to screen cytokine changes, with quantitative (q)PCR used to confirm mRNA elevations and immunoblots used for protein levels. P2X7 antagonist Brilliant Blue G (BBG) and agonist BzATP were injected intravitreally. ELISA was used to quantify IL-6 release from optic nerve head astrocytes or retinal ganglion cells. Receptor identity was confirmed pharmacologically and in P2X7(-/-) mice. RESULTS: Acute elevation of IOP altered retinal expression of multiple cytokine genes. Elevation of IL-6 was greatest, with expression of IL1m, IL24, Tnf, Csf1 and Lif also increased more than two-fold, while Tnfsf11, Gdf9 and Tnfsf4 were reduced. qPCR confirmed the rise in IL-6 and extracellular ATP marker ENTPD1, but not pro-apoptotic genes. Intravitreal injection of P2X7 receptor antagonist BBG prevented the pressure-dependent rise in IL-6 mRNA and protein in the rat retina, while injection of P2X7 receptor agonist BzATP was sufficient to elevate IL-6 expression. IOP elevation increased IL-6 in wild type but not P2X7R knockout mice. Application of mechanical strain to isolated optic nerve head astrocytes increased IL-6 levels. This response was mimicked by agonist BzATP, but blocked by antagonists BBG and A839977. Stretch or BzATP led to IL-6 release from both astrocytes and isolated retinal ganglion cells. CONCLUSIONS: The mechanosensitive upregulation and release of cytokine IL-6 from the retina involves the P2X7 receptor, with both astrocytes and neurons contributing to the response. This article is protected by copyright. All rights reserved.
Departments of Anatomy and Cell Biology, University of Pennsylvania.
Full articleClassification:
3.6 Cellular biology (Part of: 3 Laboratory methods)
3.5 Molecular biology incl. SiRNA (Part of: 3 Laboratory methods)
3.9 Pathophysiology (Part of: 3 Laboratory methods)
3.8 Pharmacology (Part of: 3 Laboratory methods)
