American Journal of Respiratory Cell and Molecular Biology最新文献

Ex vivo lung perfusion (EVLP) is a promising technique that allows organ preservation and repair, while the molecular mechanisms remain unknown. This study aimed to establish a translational murine EVLP model and to unveil the molecular mechanisms responsible for EVLP beneficial effects. We developed a murine EVLP system with four experimental groups: (1) without ischemia or EVLP (control), (2) 45 min EVLP followed by 135 min cold ischemia (EVLP-CI), (3) 135 min cold ischemia followed by 45 min EVLP (CI-EVLP), and (4) 180 min cold ischemia (CI). Following 3-hour preservation, changes in lung weight (Δweight) and lung vascular filtration coefficient (K_f) were measured. Complementary in vitro studies utilized human pulmonary microvascular endothelial cells under simulated perfusion conditions. Compared to CI group, both EVLP intervention groups exhibited superior preservation outcomes, with an attenuated Δweight and K_f, and histological and microscopic evidence of lung damage. Proteomic profiling on mouse lungs revealed that EVLP regulated the Hippo signaling in response to CI. Pharmacological inhibition (TDI-011536 or Lats-IN-1) or genetic deletion of Yap1 or Lats1 specifically in endothelial cells (Yap1^EN-KO or Lats1^EN-KO) abrogated EVLP-mediated endothelial barrier protection. EVLP efficacy in lung preservation was enhanced by Yap1 phosphorylation activation using AICAR or metformin. In vitro perfusion models recapitulated these findings, where barrier function was disrupted with Yap1 phosphorylation inhibitor, with a decreased cytoplasmic localization of Yap1. Our findings establish the functional murine EVLP model and first demonstrate that mechanical perfusion preserves donor lung viability through Hippo signaling-mediated endothelial barrier stabilization.

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by elevated pulmonary arterial pressure and right ventricular failure. The perivascular macrophages in the lungs play a crucial role in the development of PAH. Here, we tested the hypothesis that colony-stimulating factor 1 receptor (CSF1R), essential for macrophage proliferation and polarization, contributed to the progression of PAH, and targeting CSF1R could offer a potential therapeutic strategy. In the lungs of patients with PAH, we found that the number of perivascular CSF1R-positive macrophages and M2 macrophages significantly increased. In the experimental sugen/hypoxia-induced PAH model, knockdown of CSF1R in the lungs decreased right ventricular systolic pressure and the number of perivascular macrophages. Pharmacological inhibition with a CSF1R inhibitor, pexidartinib, and anti-CSF1R neutralizing antibody blocked perivascular macrophage accumulation and improved the severity of pulmonary hypertension in the murine PAH models. Mechanistically, C-C motif chemokine ligand 2 (CCL2) produced by M2 macrophages was identified as a key driver for pulmonary artery smooth muscle cell proliferation, leading to pulmonary arterial remodeling. Activation of CSF1R and c-Jun N terminal kinase (JNK) transcriptionally regulated Ccl2 expressions in macrophages. In conclusion, our study suggests that CSF1R and M2 macrophages have critical roles in the progression of PAH through CCL2.

Effective immune activation is essential for host defense against pathogenic microorganism infection. However, excessive or uncontrolled immune activation can cause tissue damage. Negative regulatory factors and immune homeostasis regulatory molecules play important roles in immune activation. CircRNAs are known to be involved in a variety of pathological and physiological processes, but their role in the regulation of host immune activation remains unclear. In this study, we identified a novel circRNA, circSlc7a11, in the lung using a Pseudomonas aeruginosa pulmonary infection model. circSlc7a11 functions as a negative regulator that prevents excessive immune activation in the host response to bacterial infection by regulating the IL-1β signaling axis through PUF60 in macrophages.

Airway mucus is a complex process influenced by various factors and signaling pathways. A key player is mammalian inositol-requiring enzyme 1 beta (IRE1β), a paralog of IRE1 alpha (IRE1α), found only in epithelial cells lining the mucosal surfaces of the gastrointestinal and respiratory tracts. IRE1β processes X-box binding protein 1 (XBP1) mRNA via its endoribonuclease (RNase) domain, generating the active XBP1 spliced form (XBP1s). XBP1s is crucial for mucin production, the main components of mucus. IRE1β is upregulated in human bronchial epithelial (HBE) cells from individuals with cystic fibrosis and asthma. Fortilin binds to IRE1α, blocking its kinase/RNase functions and preventing cell death. However, the interaction between fortilin and IRE1β, and its effects on airway mucus under basal conditions, remain unknown. We investigate whether fortilin binds IRE1β, regulates its RNase activity, and is associated with IRE1β-mediated mucin production. We find that fortilin binds to the cytosolic domain of IRE1β, significantly increasing its RNase and kinase activities. Furthermore, fortilin depletion significantly attenuates mucin 5 AC (MUC5AC) expression by reducing XBP1 splicing and AKT phosphorylation in differentiated HBE cells under air-liquid interface culture (ALI-HBE cells). IRE1 inhibitor KIRA8 blunts IRE1β kinase/RNase activities in ALI-HBE cells, inhibiting both XBP1 splicing and AKT phosphorylation regardless of fortilin presence. These data suggest that fortilin promotes IRE1β-mediated MUC5AC expression primarily via the IRE1β/XBP1 signaling pathway. The IRE1β-fortilin complex holds promise for developing innovative therapies to regulate mucin production in conditions characterized by airway mucus hypersecretion, including chronic obstructive pulmonary disease, asthma, bronchiectasis, and cystic fibrosis.