MicroRNA-223 Regulates Retinal Function and Inflammation in the Healthy and Degenerating Retina.

Nilisha Fernando,Yvette Wooff,Adrian V Cioanca,Riccardo Natoli,Ulrike Schumann,Joshua A Chu-Tan,Chinh Ngo,Rohan W Essex,Sarah A Robertson,Josephine H C Wong,Riemke Aggio-Bruce,Jan Provis,Camilla Dorian,Catherine Dietrich,Si Ming Man,Shannon Das

doi:10.3389/fcell.2020.00516

Nilisha Fernando, Yvette Wooff + Show 14 more

Open Access

https://doi.org/10.3389/fcell.2020.00516

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Abstract

IntroductionMicroRNAs (miRNAs) are small, non-coding RNA molecules that have powerful regulatory properties, with the ability to regulate multiple messenger RNAs (mRNAs) and biological pathways. MicroRNA-223-3p (miR-223) is known to be a critical regulator of the innate immune response, and its dysregulation is thought to play a role in inflammatory disease progression. Despite miR-223 upregulation in numerous neurodegenerative conditions, largely in cells of the myeloid lineage, the role of miR-223 in the retina is relatively unexplored. Here, we investigated miR-223 in the healthy retina and in response to retinal degeneration.MethodsmiR-223-null mice were investigated in control and photo-oxidative damage-induced degeneration conditions. Encapsulated miR-223 mimics were intravitreally and intravenously injected into C57BL/6J wild-type mice. Retinal functional responses were measured using electroretinography (ERG), while extracted retinas were investigated by retinal histology (TUNEL and immunohistochemistry) and molecular analysis (qPCR and FACS).ResultsRetinal function in miR-223–/– mice was adversely affected, indicating that miR-223 may be critical in regulating the retinal response. In degeneration, miR-223 was elevated in the retina, circulating serum, and retinal extracellular vesicles. Conversely, retinal microglia and macrophages displayed a downregulation of miR-223. Further, isolated CD11b+ inflammatory cells from the retinas and circulation of miR-223-null mice showed an upregulation of pro-inflammatory genes that are critically linked to retinal inflammation and progressive photoreceptor loss. Finally, both local and systemic delivery of miR-223 mimics improved retinal function in mice undergoing retinal degeneration.ConclusionmiR-223 is required for maintaining normal retinal function, as well as regulating inflammation in microglia and macrophages. Further investigations are required to determine the targets of miR-223 and their key biological pathways and interactions that are relevant to retinal diseases. Future studies should investigate whether sustained delivery of miR-223 into the retina is sufficient to target these pathways and protect the retina from progressive degeneration.

Highlights

MicroRNAs are small, non-coding RNA molecules that have powerful regulatory properties, with the ability to regulate multiple messenger RNAs and biological pathways
Genes for pro-inflammatory panels were selected on the following basis: (1) C-C motif ligand 3 (Ccl3), NLR family pyrin domain containing 3 (Nlrp3), and signal transducer and activator of transcription 3 (Stat3) are validated targets of miR-223-3p (Bauernfeind et al, 2012; Chen et al, 2012; Dorhoi et al, 2013) and are known to be involved in retinal degenerative diseases (Doyle et al, 2012; Kohno et al, 2014; Chen et al, 2016, 2019; Fernando et al, 2016; Wooff et al, 2020b); (2) we have shown that component 1qa (C1qa), component 3 (C3), and Il-1β are all critically linked to retinal disease progression in photo-oxidative damage (Natoli et al, 2017a,b; Jiao et al, 2018); and (3) cathepsin E (Ctse) is a predicted target of miR-223-3p and is involved in key inflammatory cell functions (Gantier, 2013)
We investigated reactive gliosis by staining for the marker GFAP, which showed no significant change in the intensity or area of GFAP staining between miR-223−/− and WT groups (Figures 1D–F, P > 0.05)

Summary

Introduction

MicroRNAs (miRNAs) are small, non-coding RNA molecules that have powerful regulatory properties, with the ability to regulate multiple messenger RNAs (mRNAs) and biological pathways. MicroRNA-223-3p (miR-223) is known to be a critical regulator of the innate immune response, and its dysregulation is thought to play a role in inflammatory disease progression. By binding to the 3 untranslated region (3 UTR) of a messenger RNA (mRNA), the mRNA is targeted for translational repression or degradation (reviewed in Bartel, 2004). Within the retina, miRNAs are known to play a major role in the development and disease of the photoreceptors, bipolar cells, and Müller cells (Zuzic et al, 2019), including the regulation of retinal inflammation (Anasagasti et al, 2018; Chu-Tan et al, 2018)

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