Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells Alleviate Diffuse Alveolar Hemorrhage Associated with Systemic Lupus Erythematosus in Mice by Promoting M2 Macrophage Polarization via the microRNA-146a-5p/NOTCH1 Axis

Jun 20, 2022Immunological investigations

Stem cell exosomes from umbilical cords reduce lung bleeding in lupus mice by encouraging anti-inflammatory immune cells through microRNA-146a-5p and NOTCH1

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Abstract

HUCMSC-derived exosomes significantly reduced NOTCH1 expression and inflammation in a mouse model of SLE-associated diffuse alveolar hemorrhage.

NOTCH1 expression was enhanced in mice with diffuse alveolar hemorrhage.
Exosomes from human umbilical cord mesenchymal stem cells decreased NOTCH1 levels and increased M2 macrophage polarization in lung tissues.
Overexpression of miR-146a-5p in macrophages reduced M1 markers and inflammatory factors while increasing M2 markers.
Inhibition of miR-146a-5p led to increased NOTCH1 expression and worsened lung inflammation and bleeding.
Silencing NOTCH1 reversed the effects of exosomes with miR-146a-5p inhibition, suggesting a regulatory role in macrophage polarization.

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Systemic lupus erythematosus (SLE)-associated diffuse alveolar hemorrhage (DAH) is a rare but extremely harmful condition. The current study sought to dissect the mechanisms underlying the effects of human umbilical cord mesenchymal stem cell (HUCMSC)-derived exosomes on M2 macrophage polarization in SLE-associated DAH via the microRNA (miR)-146a-5p/NOTCH1 axis. A DAH mouse model was established using pristane. Exosomes were isolated from HUCMSCs transfected or untransfected with the miR-146a-5p antagonist or agonist and their NCs and then injected into DAH mice. Additionally, miR-146a-5p was overexpressed in macrophages. Expression of miR-146a-5p, NOTCH1, M1 macrophage markers, and M2 macrophage markers was measured in mice and macrophages, and inflammatory factor levels were detected. Mouse lung injuries were evaluated, so was the binding of miR-146a-5p to NOTCH1. Rescue experiments were conducted in mice and macrophages using NOTCH1 shRNA and pcDNA3.1-NOTCH1, respectively. NOTCH1 expression was enhanced in DAH mice. HUCMSC-derived exosomes reduced NOTCH1 expression, bleeding, inflammation, and M1 macrophage polarization but elevated M2 macrophage polarization in lung tissues of DAH mice. Mechanistically, NOTCH1 is negatively targeted by miR-146a-5p. miR-146a-5p overexpression diminished M1 marker and inflammatory factor levels but enhanced M2 marker levels in macrophages, which was nullified by NOTCH1 overexpression. HUCMSC-derived exosomes with miR-146a-5p inhibition increased NOTCH1 expression, worsened bleeding and inflammation, and augmented M1 macrophage polarization while decreasing M2 macrophage polarization in lung tissues of DAH mice, which was abrogated by silencing NOTCH1. HUCMSC-derived exosomes diminished NOTCH1 expression to accelerate M2 macrophage polarization via delivery of miR-146a-5p, thus alleviating SLE-associated DAH in mice.

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Exosomes Derived from Human Umbilical Cord Mesenchymal Stem Cells Alleviate Diffuse Alveolar Hemorrhage Associated with Systemic Lupus Erythematosus in Mice by Promoting M2 Macrophage Polarization via the microRNA-146a-5p/NOTCH1 Axis

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