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Polyethyleneimine-coated Iron Oxide Nanoparticles as a Vehicle for the Delivery of Small Interfering RNA to Macrophages In Vitro and In Vivo
Published on: February 5, 2019
Systemically Silencing Long Non-coding RNAs Maclpil With Short Interfering RNA Nanoparticles Alleviates Experimental
Yan Wang1,2, Cuiying Liu3, Yong Chen1,4
1Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing, China.
Background:
Maclpil is a proinflammatory long non-coding RNA highly expressed on monocyte-derived macrophages in the ischemic brain. This study investigated the impact and the mechanisms of systemically delivering nanoparticle Maclpil short interfering RNA (siRNA) on experimental ischemic stroke in a mouse model.
Methods:
Ischemic stroke (focal cerebral ischemia) was induced in male C57BL/6 mice through the middle cerebral artery occlusion. Three hours thereafter, mice were intravenously injected with Maclpil siRNA or scramble siRNA nanoparticles. Bone marrow cell-derived macrophages were transfected with Maclpil or scramble siRNA and subjected to oxygen glucose deprivation culture. The influence of silencing Maclpil on stroke outcomes, neuroinflammation, and macrophage fates was assessed via histology, flow cytometry, Western blotting, and quantitative PCR analysis.
Results:
Three days following stroke induction, siRNA silencing Maclpil substantially reduced ischemic infarction size and improved neurological behaviors. Silencing Maclpil also markedly attenuated the accumulation of monocyte-derived macrophages, CD4+ T cells, and CD8+ T cells in the ischemic hemisphere without affecting microglia cellularity. Reciprocally, myeloid cells and both subsets of T cells were elevated in mouse peripheral blood following Maclpil siRNA treatment. Under oxygen glucose deprivation conditions that mimicked hypoxia and hypoglycemia in vitro, Maclpil siRNA silencing augmented macrophage apoptosis in conjunction with upregulation of proapoptotic Bax and caspase 3 expressions. siRNA knocking down Maclpil skewed macrophages from proinflammatory classical toward anti-inflammatory alternative activation as evidenced by increased arginase 1, Ym1, and Fizz1 and reduced inducible nitric oxide synthase, IL-1β, and TNF-α mRNA levels. Consistent with macrophage phenotype switching, silencing Maclpil by siRNA enhanced fatty acid oxidation as indicated by increased mRNA levels of 3 key metabolic enzymes (ACADM, ACADVL, and HADHA).
Conclusion:
Systemically silencing Maclpil by siRNA nanoparticles attenuated experimental ischemic stroke by promoting macrophage apoptosis and anti-inflammatory alternative activation. Identifying and targeting Maclpil human homolog(s) may help develop a novel therapy for stroke clinical management.
Insights
Systemic delivery of Maclpil short interfering RNA (siRNA) nanoparticles reduced stroke size and improved outcomes by promoting macrophage apoptosis and anti-inflammatory responses. Targeting Maclpil may offer a novel therapeutic strategy for ischemic stroke.
Area of Science:
- Neuroscience
- Molecular Biology
- Immunology
Background:
- Maclpil is a proinflammatory long non-coding RNA highly expressed on monocyte-derived macrophages in the ischemic brain.
- Experimental ischemic stroke models are crucial for understanding disease mechanisms and testing therapies.
Purpose of the Study:
- To investigate the impact of systemically delivered Maclpil short interfering RNA (siRNA) nanoparticles on experimental ischemic stroke.
- To elucidate the mechanisms by which Maclpil silencing affects neuroinflammation and macrophage function.
Main Methods:
- Ischemic stroke was induced in mice via middle cerebral artery occlusion.
- Mice received intravenous injections of Maclpil siRNA or scramble siRNA nanoparticles.
- Macrophage apoptosis, cellularity, T cell accumulation, and gene expression were analyzed.
Main Results:
- Maclpil siRNA significantly reduced infarct size and improved neurological behaviors.
- Maclpil silencing decreased monocyte-derived macrophages and T cells in the brain but increased them in peripheral blood.
- Maclpil siRNA promoted macrophage apoptosis and skewed macrophages toward an anti-inflammatory phenotype, enhancing fatty acid oxidation.
Conclusions:
- Systemic silencing of Maclpil attenuates experimental ischemic stroke by promoting macrophage apoptosis and anti-inflammatory alternative activation.
- Targeting Maclpil may represent a novel therapeutic approach for clinical stroke management.
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