Yongmei Cao

Background: Despite advances in therapeutic strategies, acute respiratory distress syndrome (ARDS) mortality remains high. Growing evidence links respiratory microbiome composition to ARDS outcomes. This investigation sought to elucidate how colonizing bacteria and their metabolites influence ARDS pathogenesis. Methods: Bronchoalveolar lavage fluid (BALF) from patients with pulmonary infections was analyzed by metagenomic next-generation sequencing (mNGS) to identify characteristic bacteria. Bacterial culture supernatants were analyzed by untargeted metabolomics (LC-MS) to identify metabolites. A murine ARDS model was established through intratracheal LPS instillation. Single-cell sequencing datasets from the GEO database were analyzed to reveal differential cell populations and functional alterations in murine ARDS. Potential molecular mechanisms were explored through molecular docking, RNA-seq analysis, Western boltting, and targeted gene knockdown in murine and cellular model. Results: R. mucilaginosa demonstrated enrichment in patients without ARDS (nARDS). The bacterial culture supernatant conferred substantial protection in murine models, whereas viable bacteria showed minimal efficacy. LC-MS analysis identified indole-3-acetaldehyde (IAAld) as the predominant metabolite in the supernatant. Single-cell sequencing suggested that resident alveolar macrophages (RAMs) were pivotal cells in murine ARDS model. IAAld enhanced RAMs phagocytosis, facilitating neutrophil and LPS clearance. Mechanistic studies revealed that IAAld likely activated PXR signaling, promoted NRF2 nuclear translocation, and upregulated the phagocytosis-related gene CD36 . Targeted PXR knockdown eliminated these protective effects. Conclusion: The respiratory commensal R. mucilaginosa synthesizes IAAld, which—independent of bacterial colonization per se—ameliorates ARDS through PXR/NRF2/CD36 axis activation, thereby enhancing macrophage phagocytic function. These findings suggest that therapeutic targeting of microbial metabolites represents a novel ARDS treatment paradigm.

The purpose of this research is to elucidate the molecular mechanisms by which bone marrow mesenchymal stem cell‐derived exosomes ( BMSCs ‐Exos) improve acute lung injury ( ALI ) through the regulation of alveolar macrophage polarization. BMSCs ‐Exos were prepared and used to pretreat mouse alveolar macrophages ( MH ‐S), followed by stimulation with LPS and IFN ‐γ. The binding interaction between miR ‐137‐3p and the 3′ untranslated region (3′UTR) of TRIM24 mRNA was confirmed through luciferase reporter assays. BMSCs ‐Exos were used to treat MH ‐S cells stimulated with LPS and IFN ‐γ, then TRIM24 protein expression, STAT6 acetylation, and reactive oxygen species ( ROS ) production were analyzed, along with the mRNA levels of macrophage polarization‐related genes. The ALI mouse model was established by intratracheal instillation of LPS , followed by intratracheal administration of BMSCs ‐Exos. Subsequently, lung histopathology, pulmonary function, wet‐to‐dry weight ratio and the levels of inflammatory cytokines in bronchoalveolar lavage fluid ( BALF ) were evaluated. LPS and IFN ‐γ stimulation significantly increased the levels of TNF ‐α, IL ‐1β, and IL ‐10 in culture supernatants, as well as CD86 and CD163 mRNA expressions in MH ‐S cells. Treatment with BMSCs ‐Exos significantly decreased TNF ‐α, IL ‐1β, and CD86 levels while increasing CD163 and IL ‐10 levels. MiR ‐137‐3p inhibits TRIM24 protein expression by binding to the 3′UTR of its mRNA . BMSCs upregulated miR ‐137‐3p and suppressed TRIM24 protein expression in MH ‐S cells co‐cultured with BMSCs , effects that were abolished by GW4869 treatment or by silencing miR ‐137‐3p in BMSCs . In LPS and IFN‐y‐induced MH‐S cells, treatment with BMSCs ‐Exos effectively upregulated miR ‐137‐3p levels and downregulated the TRIM24 expression, which in turn promoted the expression of M2 polarization‐related genes Arg1 and Fizz1, while inhibiting the expression of the M1 polarization gene Nos2 and reducing ROS production. In vivo, intratracheal administration of BMSCs ‐Exos alleviated pulmonary inflammation and injury in ALI mice and enhanced M2 polarization of alveolar macrophages. BMSCs ‐Exos promote M2 polarization and inhibit M1 polarization of alveolar macrophages by delivering miR ‐137‐3p, thereby significantly improving lung injury.

Patients with sepsis-induced acute respiratory distress syndrome (ARDS) have higher mortality and poor prognosis than pneumonia-induced ARDS. Pulmonary fibrosis is an irreversible accumulation of connective tissue in the interstitium of the lung and closely associated with the epithelial–mesenchymal transition (EMT) of type II alveolar epithelial cells (AECIIs). Therefore, it is undoubtedly worth studying whether the EMT of AECIIs in sepsis-induced ARDS patients is different from that in patients with pneumonia-induced ARDS in the regulatory mechanism. Here, we will report for the first time that an lncRNA-ASLNC12002 is highly expressed in AECIIs of patients with sepsis-induced pneumonia and promotes EMT in AECIIs. The research results showed that the expression of ASLNC12002 in AECIIs derived from patients with sepsis-induced ARDS is significantly higher than that in normal people and pneumonia-induced ARDS patients. Mechanism research showed that ASLNC12002 can cause the inactivation of the anti-EMT pathway NR2F2/miR128-3p/Snail1 by acting as the sponge of miR128-3p. Functional experiments showed that targeted silencing of ASLNC12002 could effectively inhibit EMT progression in AECIIs of patients with sepsis-induced pneumonia by restoring NR2F2/miR128-3p/Snail1 pathway. In a word, our study shows for the first time that the inactivation of NR2F2/miR128-3p/Snail1 pathway caused by the enhanced expression of ASLNC12002 is the direct reason why AECIIs in sepsis-induced ARDS patients are prone to get EMT progress. ASLNC12002 has the potential to become a biological target for the prevention and treatment of pulmonary fibrosis in patients with sepsis-induced ARDS. At the same time, the expectation that ASLNC12002 and its related products may be used as clinical markers for the evaluation of early pulmonary fibrosis in ARDS patients should not be ignored.

Background. Postoperative cognitive dysfunction (POCD) is a common complication after abdominal surgery. Several studies have reported that POCD is related to neuroinflammation caused by surgery. Omega‐3 polyunsaturated fatty acids (PUFAs) can effectively inhibit the systematic inflammatory response. So, we use fish oil to study the effect of fish oil on inflammation, immunity, and cognitive behavior after splenectomy in rats. Methods. 60 SD (Sprague‐Dawley) rats were randomly divided into control group (group C, n = 20), surgery group (group S, n = 20), and omega‐3 (fish oil) intervention group (group F, n = 20). Omega‐3 PUFA was injected intraperitoneally from 3 days before operation to 7 days after operation in group F, and normal saline was injected simultaneously in group S. Rats in group S and group F received splenectomy under general anesthesia. Morris water maze behavioral evaluation was performed on the first, third, fifth, and seventh day after operation. The levels of IL‐1β (interleukin‐1β), IL‐6 (interleukin‐6), TNF‐α (tumor necrosis factor‐α), SOD (superoxide dismutase), and GSH‐PX (glutathione peroxidase) were detected. Results. Serums IL‐1β, IL‐6, and TNF‐α concentrations in group S and group F were higher than those in group C (P < 0.01), while those inflammatory cytokines in group F were significantly lower than those in group S (P < 0.01); serum GSH‐PX levels in group F were higher than group S (P < 0.01). The Morris water maze behavior test performance of group F was better than that of group S (P < 0.05). Conclusion. Omega‐3 PUFA can effectively improve postoperative inflammatory response, reduce the damage of antioxidant defense system, and improve postoperative cognitive function.

BackgroundAmong several leading cardiovascular disorders, ischemia-reperfusion (I/R) injury causes severe manifestations including acute heart failure, inflammation, and systemic dysfunction. Recently, there has been increasing evidence suggesting that alterations in mitochondrial morphology play a role in the prognoses of cardiac disorders. Long non-coding RNAs (lncRNAs) form major regulatory networks to modify gene transcription and translation. While several roles of lncRNAs have been explored in cancer and tumor biology, their implications on mitochondrial morphology and functions remain to be elucidated. MethodsThe functional roles of ZFP36L2 and lncRNA PVT1 were determined by a series of cardiomyocyte hypoxia/ reoxygenation (H/R) in vitro and myocardial I/R injury in vivo experiments. Quantitative Reverse transcription-polymerase chain reaction (qRT-PCR) and western blot analysis were used to detect the mRNA levels of ZFP36L2 and mitochondrial fission and fusion markers in the myocardial tissues and cardiomyocyte. Cardiac function was determined by immunohistochemistry, H&E, Masson’s staining and echocardiogram. Ultrastructural analysis of mitochondrial fission was performed using transmission electron microscopy (TEM). The mechanistic model of PVT1 with ZFP36L2 and miR-21-5p with MARCH5 was detected by subcellular fraction, RNA pull down, FISH, and luciferase reporter assays.ResultsIn this study, we report a novel regulatory axis involving lncRNA PVT1, microRNA miR-21-5p, and E3 ubiquitin ligase MARCH5, which alters mitochondrial morphology during myocardial I/R injury. Using an in vivo I/R injury mouse model and in vitro cardiomyocyte H/R model, we observed that zinc finger protein ZFP36L2 directly associated with PVT1 and altered mitochondrial fission and fusion. PVT1 also interacted with miR-21-5p and suppressed its expression and activity. Furthermore, we identified MARCH5 as a modifier of miR-21-5p, and expression of MARCH5 and its effect on mitochondrial fission and fusion were directly proportional to PVT1 expression during H/R injury. ConclusionsOur findings demonstrated that manipulation of PVT1-miR-21-5p-MARCH5-mediated mitochondrial fission and fusion via ZFP36L2 may be a novel therapeutic approach to regulate myocardial I/R injury.

The balance between Ang II/AT1R and Ang‐(1‐7)/Mas plays a pivotal role in the development of lipopolysaccharides (LPS)‐induced acute respiratory distress syndrome. However, the mechanisms underlying the balancing process still remain unclear. Here we investigated the roles of nuclear factor (NF)‐κB and p53 in regulating AT1R and Mas expression. The results demonstrated that Ang II pretreatment resulted in downregulation of Mas and upregulation of AT1R, phosphorylated p65, and apoptosis in LPS‐treated Human pulmonary microvascular endothelial cells (HPMVECs), but had no effect on p53 expression. Lentiviral vector‐mediated P65 knockdown, but not a P53 knockdown, reversed all these effects of Ang II. On the other hand, Ang‐(1‐7) pretreatment lead to an increased in Mas expression and a decrease in AT1R, p53, and phosphorylated p65 expressions with suppressed apoptosis in LPS‐treated cells. P65 knockdown promoted the protein expression of both AT1R and Mas while inhibiting p53 expression. P53 knockdown, but not a p65 knockdown, reversed all these effects of Ang‐(1‐7). Interestingly, p65 overexpression upregulated p53 and AT1R but downregulated Mas. P53 knockdown activated p65. These results suggest that there is a two‐way feedback regulation between AT1R and Mas receptor via the NF‐kB p65/P53 pathway, which may play a key role in LPS‐induced HPMVECs apoptosis.