p38-mediated FOXN3 phosphorylation modulates lung inflammation and injury through the NF-κB signaling pathway.

NF-κB activates the primary inflammatory response pathway responsible for methicillin-resistant Staphylococcus aureus (MRSA)-induced lung inflammation and injury. Here, we report that the Forkhead box transcription factor FOXN3 ameliorates MRSA-induced pulmonary inflammatory injury by inactivating NF-κB signaling. FOXN3 competes with IκBα for binding to heterogeneous ribonucleoprotein-U (hnRNPU), thereby blocking ß-TrCP-mediated IκBα degradation and leading to NF-κB inactivation. FOXN3 is directly phosphorylated by p38 at S83 and S85 residues, which induces its dissociation from hnRNPU, thus promoting NF-κB activation. After dissociation, the phosphorylated FOXN3 becomes unstable and undergoes proteasomal degradation. Additionally, hnRNPU is essential for p38-mediated FOXN3 phosphorylation and subsequent phosphorylation-dependent degradation. Functionally, genetic ablation of FOXN3 phosphorylation results in strong resistance to MRSA-induced pulmonary inflammatory injury. Importantly, FOXN3 phosphorylation is clinically positively correlated with pulmonary inflammatory disorders. This study uncovers a previously unknown regulatory mechanism underpinning the indispensable role of FOXN3 phosphorylation in the inflammatory response to pulmonary infection.

Extracellular vesicle-transmitted miR-671-5p alleviates lung inflammation and injury by regulating the AAK1/NF-κB axis.

Mesenchymal stem cells regulate remote intercellular signaling communication via their secreted extracellular vesicles. Here, we report that menstrual blood-derived stem cells alleviate acute lung inflammation and injury via their extracellular vesicle-transmitted miR-671-5p. Disruption of this abundantly expressed miR-671-5p dramatically reduced the ameliorative effect of extracellular vesicles released by menstrual blood-derived stem cells on lipopolysaccharide (LPS)-induced pulmonary inflammatory injury. Mechanistically, miR-671-5p directly targets the kinase AAK1 for post-transcriptional degradation. AAK1 is found to positively regulate the activation of nuclear factor κB (NF-κB) signaling by controlling the stability of the inhibitory protein IκBα. This study identifies a potential molecular basis of how extracellular vesicles derived from mesenchymal stem cells improve pulmonary inflammatory injury and highlights the functional importance of the miR-671-5p/AAK1 axis in the progression of pulmonary inflammatory diseases. More importantly, this study provides a promising cell-based approach for the treatment of pulmonary inflammatory disorders through an extracellular vesicle-dependent pathway.

miR-328-5p functions as a critical negative regulator in early endothelial inflammation and advanced atherosclerosis.

Early proatherogenic inflammation constitutes a significant risk factor for atherogenesis development. Despite this, the precise molecular mechanisms driving this pathological progression largely remain elusive. Our study unveils a pivotal role for the microRNA miR-328-5p in dampening endothelial inflammation by modulating the stability of JUNB (JunB proto-oncogene). Perturbation of miR-328-5p levels results in heightened monocyte adhesion to endothelial cells and enhanced transendothelial migration, while its overexpression mitigates these inflammatory processes. Furthermore, miR-328-5p hinders macrophage polarization toward the pro-inflammatory M1 phenotype, and exerts a negative influence on atherosclerotic plaque formation in vivo. By pinpointing JUNB as a direct miR-328-5p target, our research underscores the potential of miR-328-5p as a therapeutic target for inflammatory atherosclerosis. Reintroduction of JUNB effectively counteracts the anti-atherosclerotic effects of miR-328-5p, highlighting the promise of pharmacological miR-328-5p targeting in managing inflammatory atherosclerosis.