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Inhibition of miR-155-5p Exerts Anti-Fibrotic Effects in Silicotic Mice by Regulating Meprin ?.

ABSTRACT: Silicosis is a fatal profession-related disease linked to long-term inhalation of silica. The present study aimed to determine whether meprin ?, a master regulator of anti-fibrotic peptide N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), is diminished by miR-155-5p in silicotic and control lung macrophages and fibroblasts upon activation. NR8383 macrophages, primary lung fibroblasts, and mouse embryonic fibroblasts were used to evaluate the expression and function of meprin ? and miR-155-5p. In vitro meprin ? manipulation was performed by recombinant mouse meprin ? protein, actinonin (its inhibitor), and small interfering RNA knockdown. Macrophage and fibroblast activation was assessed by western blotting, real-time PCR, matrix deposition, and immunohistochemical staining. The roles of meprin ? and miR-155-5p were also investigated in mice exposed to silica. We found that the meprin ? level was stably repressed in silicotic rats. In vitro, silica decreased meprin ?, and exogenous meprin ? reduced activation of macrophages and fibroblasts induced by profibrotic factors. miR-155-5p negatively regulated Mep1a by binding to the 3' untranslated region. Treatment with anti-miR-155-5p elevated meprin ?, ameliorated macrophage and fibroblast activation, and attenuated lung fibrosis in mice induced by silica. The sustained repression of meprin ? and beneficial effects of its rescue by inhibition of miR-155-5p during silicosis indicate that miR-155-5p/meprin ? are two of the major regulators of silicosis.

SUBMITTER: Chen Y

PROVIDER: S-EPMC6939030 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Inhibition of miR-155-5p Exerts Anti-Fibrotic Effects in Silicotic Mice by Regulating Meprin α.

Chen Yingying Y Xu Dingjie D Yao Jingxin J Wei Zhongqiu Z Li Shifeng S Gao Xuemin X Cai Wenchen W Mao Na N Jin Fuyu F Li Yaqian Y Zhu Ying Y Li Shumin S Liu Heliang H Yang Fang F Xu Hong H

Molecular therapy. Nucleic acids 20191126

Silicosis is a fatal profession-related disease linked to long-term inhalation of silica. The present study aimed to determine whether meprin α, a master regulator of anti-fibrotic peptide N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP), is diminished by miR-155-5p in silicotic and control lung macrophages and fibroblasts upon activation. NR8383 macrophages, primary lung fibroblasts, and mouse embryonic fibroblasts were used to evaluate the expression and function of meprin α and miR-155-5p. In ...[more]

PMID: 31877411

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Project description:BackgroundToxoplasma gondii is a zoonotic intracellular protozoon that is estimated to infect about 30% of the world's population, resulting in toxoplasmosis in immunocompromised patients and adverse outcomes in cases of primary infection during pregnancy. Exosomes are tubular vesicles secreted by cells, and function in intercellular communication. It has been reported that the exosomes secreted by T. gondii-infected immune cells transmit infection signals to the uninfected cells. However, the mechanism and effect of the exosome transmission are still vague. We therefore investigated the function of the exosomes transmitted from DC2.4 cells infected with the T. gondii RH strain (Tg-DC-Exo) to the uninfected cells, as well as their roles in anti-infection.MethodsWe conducted exosome isolation and identification with ultracentrifugation, transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blot (WB) analysis. Exosome uptake by recipient cells was identified by PKH67 assay. The signal transmission and the abundance of miR-155-5p were determined using transwell assay and qRT-PCR. For detection of immune responses, cytokine secretion was evaluated. The T. gondii B1 gene was determined to evaluate tachyzoite proliferation.ResultsWe observed that Toxoplasma infection upregulated miR-155-5p expression in DC2.4 cell-secreted exosomes, and those exosomes could be ingested by murine macrophage RAW264.7 cells. Tg-DC-Exo and miR-155-5p stimulated host proinflammatory immune responses including increased production of proinflammatory cytokines IL-6 and TNF-α, and proinflammatory marker-inducible nitric oxide synthase (iNOS). The NF-κB pathway was activated by downregulation of SOCS1, leading to inhibition of T. gondii tachyzoite proliferation in RAW264.7 cells.ConclusionsOur findings provide a novel mechanism for how infected cells transmit infection signals to the uninfected cells through exosome secretion after T. gondii infection, followed by inflammatory responses and anti-infection reactions, which may help us develop a new strategy for toxoplasmosis prevention, especially in immunocompromised patients.

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Inhibition of miR-155-5p Exerts Anti-Fibrotic Effects in Silicotic Mice by Regulating Meprin ?.

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Inhibition of miR-155-5p Exerts Anti-Fibrotic Effects in Silicotic Mice by Regulating Meprin α.

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