Loss of MBD2 ameliorates LPS‐induced alveolar epithelial cell apoptosis and ALI in mice via modulating intracellular zinc homeostasis

Network pharmacology analysis and experimental validation of Xiao-Qing-Long-Tang's therapeutic effects against neutrophilic asthma

BACKGROUND

Xiao-Qing-Long-Tang (XQLT), a classical Chinese herbal medicine formula, has been extensively used for allergic asthma treatment. However, there is limited research on its anti-inflammatory effects and mechanisms specifically in neutrophilic asthma (NA).

PURPOSE

This study aims to investigate the potential therapeutic effects of XQLT against NA using a combination of network pharmacology and experimental validation.

STUDY DESIGN

By utilizing traditional Chinese medicine and disease databases, we constructed an XQLT-asthma network to identify potential targets of XQLT for NA. In the experimental phase, we utilized an ovalbumin (OVA)/lipopolysaccharide (LPS)-induced model for neutrophilic asthma and examined the therapeutic effects of XQLT.

RESULTS

Our research identified 174 bioactive components within XQLT and obtained 140 target genes of XQLT against asthma. Functional enrichment analysis revealed that these target genes were primarily associated with inflammation and cytokines. In the experimental validation, mice induced with OVA-LPS showcased eosinophilic and neutrophilic cell infiltration in peri-bronchial areas, elevated levels of IL-4 and IL-17 in both serum and lung, increased percentages of Th2 and Th17 cells in the spleen, as well as elevated levels of CD11b+ and CD103+ dendritic cells (DCs) within the lung. Treatment with XQLT effectively reduced IL-4 and IL-17 levels, decreased the percentages of Th2, Th17, CD11b+, and CD103+ DCs, and improved inflammatory cell infiltrations in lung tissues. These findings serve as a foundation for the potential clinical application of XQLT in neutrophilic asthma.

Mechanisms underlying the synergistic effects of chuanxiong combined with Chishao on treating acute lung injury based on network pharmacology and molecular docking combined with preclinical evaluation

ETHNOPHARMACOLOGICAL RELEVANCE

The herb pair of Chuanxiong Rhizome (Ligusticum chuanxiong Hort., Chuanxiong in Chinese, CX) and Paeoniae Radix Rubra (Paeonia lactiflora Pall. Or Paeonia veitchii Lynch, Chishao in Chinese, CS) is a famous blood activating and stasis resolving pair that is often found in traditional Chinese medicine (TCM) formulas for the treatment of acute lung injury (ALI). However, the relationship of CX-CS herb pair to ALI and its underlying mechanisms are unclear.

AIM OF THE STUDY

The study explored the effect and mechanisms of CX-CS herb pair in LPS induced ALI by network pharmacology and molecular docking combined with preclinical evaluation.

MATERIALS AND METHODS

The related targets of the active compounds of CX-CS herb pair in regulating ALI were screened by network pharmacology. PPI was constructed and the potential pathways were investigated by GO and KEGG. The contribution of each active ingredient of CX-CS herb pair to ALI were calculated by network-based efficacy. The interactions between potential targets and active ingredients were evaluated by molecular docking. LPS stimulated RAW264.7 cells and mice model experiments were adopted to verify the effect of CX-CS herb pair on ALI.

RESULTS

A total of 25 compounds and 193 targets were identified in the CX-CS herb pair, of which 19 compounds and 64 targets were associated with ALI, and six compounds including baicalin, ellagic acid, baicalein, beta-sitosterol, paeoniflorin and ferulic acid accounted for 93.12% of the total combination index for ALI prevention. The CX-CS herbal pair against ALI was associated with PI3K/AKT and MAPK signaling pathways by GO and KEGG analysis. The screened active compounds showed good affinity for TNF, MAPK, and AKT by molecular docking. In vitro and in vivo tests showed that CX combined with CS synergistically inhibited LPS-induced ALI at 1:3, suppressed the release of TNF-α, IL-1β and IL-6, inhibited the accumulation of ROS, as well as regulated the content of SOD, MDA and GSH. Meanwhile, the herb pair was effective in inhibiting the expression of p38, ERK, IκBα, p65, caspase 3, PARP, and up-regulating the levels of AKT and Bcl-2/Bax.

CONCLUSIONS

Our study confirmed the synergistic effect of CX-CS herb pair on the prevention of ALI by inhibiting inflammation, oxidative stress, and apoptosis through MAPK/NF-κB and PI3K/AKT signaling pathways.

Inhibition of METTL3 alleviated LPS-induced alveolar epithelial cell apoptosis and acute lung injury via restoring neprilysin expression

AIMS

To investigate the role and mechanisms of methyltransferase-like 3 (METTL3) in the pathogenesis of lipopolysaccharide (LPS)-induced acute lung injury (ALI).

MAIN METHODS

LPS intratracheally instillation was applied in alveolar epithelial cell METTL3 conditional knockout (METTL3-CKO) mice and their wild-type littermates. In addition, METTL3 inhibitor STM2457 was used. LPS treatment on mouse lung epithelial 12 (MLE-12) cell was applied to establish an in vitro model of LPS-induced ALI. H&E staining, lung wet-to-dry ratio, and total broncho-alveolar lavage fluid (BALF) concentrations were used to evaluate lung injury. Overall, the m6A level was determined with the m6A RNA Methylation Quantification Kit and dot blot assay. Expression of METTL3 and neprilysin were measured with immunohistochemistry, immunofluorescence, immunofluorescence-fluorescence in situ hybridization, and western blot. Apoptosis was detected with TUNEL, western blot, and flow cytometry. The interaction of METTL3 and neprilysin was determined with RIP-qPCR and MeRIP.

KEY FINDINGS

METTL3 expression and apoptosis were increased in alveolar epithelial cells of mice treated with LPS, and METTL3-CKO or METTL3 inhibitor STM2457 could alleviate apoptosis and LPS-induced ALI. In MLE-12 cells, LPS-Induced METTL3 expression and apoptosis. Knockdown of METTL3 alleviated, while overexpression of METTL3 exacerbated LPS-induced apoptosis. LPS treatment reduced neprilysin expression, the intervention of neprilysin expression negatively regulated apoptosis without affecting METTL3 expression, and mitigated the promoting effect of METTL3 on LPS-induced apoptosis. Additionally, METTL3 could bind to the mRNA of neprilysin, and reduce its expression.

SIGNIFICANCE

Our findings revealed that inhibition of METTL3 could exert anti-apoptosis and ALI-protective effects via restoring neprilysin expression.

BMSC-Derived Exosomes Alleviate Sepsis-Associated Acute Respiratory Distress Syndrome by Activating the Nrf2 Pathway to Reverse Mitochondrial Dysfunction

Type II alveolar epithelial cell (AECII) apoptosis is one of the most vital causes of sepsis-induced acute respiratory distress syndrome (ARDS). Recent evidence has proved that bone mesenchymal stem cell-derived exosomes (BMSC-exos) can effectively reduce sepsis-induced ARDS. However, the function and molecular mechanism of BMSC-exos in sepsis-induced AECII apoptosis remain to be elucidated. In the present study, a more significant number of AECII apoptosis, high mitochondrial fission p-Drp1 protein levels, and low levels of mitochondrial biogenesis-related PGC1α, Tfam, and Nrf1 proteins accompanied with ATP content depression were confirmed in AECIIs in response to sepsis. Surprisingly, BMSC-exos successfully recovered mitochondrial biogenesis, including the upregulated expression of PGC1α, Tfam, Nrf1 proteins, and ATP contents, and prohibited p-Drp1-mediated mitochondrial fission by promoting Nrf2 expression. However, the aforementioned BMSC-exo reversal of mitochondrial dysfunction in AECIIs can be blocked by Nrf2 inhibitor ML385. Finally, BMSC-exos ameliorated the mortality rate, AECII apoptosis, inflammatory cytokine storm including HMGB1 and IL-6, and pathological lung damage in sepsis mice, which also could be prevented by ML385. These findings reveal a new mechanism of BMSC-exos in reversing mitochondrial dysfunction to alleviate AECII apoptosis, which may provide novel strategies for preventing and treating sepsis-induced ARDS.

Ferulic acid alleviates alveolar epithelial barrier dysfunction in sepsis-induced acute lung injury by activating the Nrf2/HO-1 pathway and inhibiting ferroptosis

CONTEXT

Ferulic acid (FA) has antioxidative and anti-inflammatory effects, and is a promising drug to treat sepsis.

OBJECTIVE

To study the therapeutic effect of FA in sepsis-induced acute lung injury (ALI) and its underlying mechanisms.

MATERIALS AND METHODS

The caecal ligation and puncture (CLP) manoeuvre was applied to establish a murine model of sepsis-induced ALI, and female BALB/c mice (6 mice per group) were subjected to 100 mg/kg FA or 0.8 mg/kg ferrostatin-1 (Fer-1, ferroptosis inhibitor) treatment to clarify the role of FA in preserving alveolar epithelial barrier function and inhibiting ferroptosis. Lipopolysaccharide (LPS; 500 ng/mL)-induced cell models were prepared and subjected to FA (0.1 μM), sh-Nrf2, and Fe (Fe-citrate, ferroptosis inducer; 5 M) treatment to study the in vitro effect of FA on LPS-induced alveolar epithelial cell injury and the role of the Nrf2/HO-1 pathway.

RESULTS

We found that FA decreased the lung injury score (48% reduction), lung wet/dry weight ratio (33% reduction), and myeloperoxidase activity (58% reduction) in sepsis-induced ALI. Moreover, FA inhibited ferroptosis of alveolar epithelial cells and improved alveolar epithelial barrier dysfunction. The protective role of FA against alveolar epithelial barrier dysfunction could be reversed by the ferroptosis inducer Fe-citrate, suggesting that FA alleviates alveolar epithelial barrier dysfunction by inhibiting ferroptosis. Mechanistically, we found that FA inhibited ferroptosis of alveolar epithelial cells by activating the Nrf2/HO-1 pathway.

CONCLUSION

Collectively, our data highlighted the alleviatory role of ferulic acid in sepsis-induced ALI by activating the Nrf2/HO-1 pathway and inhibiting ferroptosis, offering a new basis for sepsis treatment.

MiR-6918-5p prevents renal tubular cell apoptosis by targeting MBD2 in ischemia/reperfusion-induced AKI

AIMS

Although previous studies reported that miRNAs are involved in the progression of acute kidney injury (AKI), their exact function and mechanism in ischemic AKI remains largely unknown. This study aims to define the role of miR-6918-5p in ischemia-reperfusion AKI. Materials and methods The renal arteries of C57BL/6J mice were clamped to establish a model of ischemia-reperfusion renal injury. BUMPT cells were added with Antimycin A and calcium ionophore to establish a model of ATP depletion in vitro. Cell apoptosis was detected by CCK8, flow cytometry and western blot, while HE staining and TUNEL staining were used to assess the degree of kidney damage.

KEY FINDINGS

We suppressed mmu_miR-6918-5p by ischemic injury in vitro and in vivo. We found that ischemia-reperfusion (I/R)-induced renal tubular cell apoptosis and the expression of cleaved caspase3 were enhanced by the inhibitor of mmu_miR-6918-5p; this effect was attenuated by an mmu_miR-6918-5p mimic. Mechanistically, mmu_miR-6918-5p binds to the 3' UTR region of MBD2 and represses its expression. The mmu_miR-6918-5p mimic alleviated the ischemic AKI by targeting MBD2. Conversely, the inhibitor of mmu_miR-6918-5p enhanced the ischemic AKI; this was diminished by MBD2-KO.

SIGNIFICANCE

Mmu_miR-6918-5p protected against the development of ischemic AKI by targeting MBD2.