Experimental Lung Research最新文献

Background: Lung injury induced by Klebsiella pneumoniae infection presents a significant challenge, with complex molecular mechanisms driving tissue damage and immune dysregulation. This study aimed to establish a zebrafish model of K. pneumoniae-induced lung injury to explore the underlying molecular mechanisms involved in tissue damage, immune responses, and development.

Methods: A zebrafish model was developed by injecting K. pneumoniae into the swim bladder at 96 h post-fertilization (hpf). The immune response, including neutrophil migration and cytokine secretion, was assessed through histological analysis and quantitative measures. Transcriptomic analysis was performed to evaluate gene expression changes related to lung development, immune regulation, and metabolism. The role of the TGF-β signaling pathway in immune response and tissue repair was investigated using the TGF-β inhibitor SB 431542.

Results: Infection with K. pneumoniae induced rapid neutrophil migration and the secretion of inflammatory cytokines such as IL-6, IL-1β, TNF-α, and TNF-β, similar to immune responses seen in mouse models. Transcriptomic analysis revealed significant alterations in genes involved in lung development, immune responses, and metabolic pathways, underscoring the broad impact of infection on physiological regulation. The TGF-β signaling pathway was found to play a dual role: it promoted immune cell recruitment and cytokine secretion but suppressed developmental genes, delaying tissue repair. Treatment with SB 431542 reduced neutrophil aggregation, lowered cytokine levels, and restored gene expression related to development and repair.

Conclusions: This zebrafish model effectively mimics K. pneumoniae-induced lung injury, offering valuable insights into the molecular mechanisms of tissue damage and immune dysregulation. Targeting the TGF-β signaling pathway holds therapeutic potential for reducing inflammation and promoting tissue repair, providing a foundation for the development of new treatment strategies for lung infections.

Aim/Purpose of the study: Acute lung injury (ALI) is a severe respiratory disease with high mortality, mainly due to overactivated oxidative stress and subsequent pyroptosis. Mesencephalic astrocyte-derived neurotrophic factor (MANF), an inducible secretory endoplasmic reticulum (ER) stress protein, inhibits lipopolysaccharide (LPS)-induced acute lung injury (ALI). However, the exact molecular mechanism remains unclear. Peroxiredoxin 6 (PRDX6), a peroxidase with a dual enzymatic function, is essential in regulating oxidative stress, which is closely associated with ALI. Furthermore, PRDX6 is an interacting protein of MANF. Therefore, this study aims to investigate the role of PRDX6 in the protective effect of MANF on ALI.

Materials and Methods: In this study, we used LPS to establish the LPS-induced ALI model. Recombinant human MANF was administrated to wide-type (WT) and PRDX6 knockout (PRDX6^-/-) rats.

Results: In WT rats, MANF reversed the increases of PRDX6, ROS overgeneration, and pyroptosis-related protein-Gasdermin D (GSDMD) induced by LPS challenge. In PRDX6^-/- rats, ROS generation, the protein level of GSDMD-N, and lung injury were not significantly decreased after human recombinant MANF administration in LPS-induced ALI.

Conclusions: PRDX6 is involved in the protective role of MANF on ALI. It is a key target molecule for MANF to exert ALI inhibitory effects.

Purpose: Chronic obstructive pulmonary disease (COPD) is a persistent inflammatory disorder characterized by minor airway inflammation and emphysema involving various cell types and cytokines. MicroRNAs (miRNAs) have emerged as critical regulators in the pathogenesis of lung diseases. This study investigates the impact of microRNA-24 (miR-24) on airway inflammatory responses in a rat model of COPD.

Materials and methods: The model was established by combining cigarette smoke exposure and lipopolysaccharide stimulation, and rat lung tissues were transfected with adeno-associated viruses overexpressing miR-24. Pathological changes in the lung were assessed using hematoxylin and eosin staining. Levels of pro-inflammatory cytokines, including tumor necrosis factor-alpha, interleukin-6, and interleukin-8, were measured using enzyme-linked immunosorbent assay. Expression of miR-24 and S100A8 was detected through quantitative reverse transcription PCR, while protein levels of S100A8, Toll-like receptor 4 (TLR4), and myeloid differentiation primary response 88 (MyD88) were assessed using western blotting. Bioinformatics analysis and dual-luciferase reporter assay were performed to determine the relationship between S100A8 and miR-24.

Results: The results demonstrated the downregulation of miR-24 in rats with COPD, and its overexpression resulted in a significant decrease in S1008 mRNA levels. Additionally, the protein level of S100A8 was significantly increased in the lung tissues of COPD rats. The upregulation of miR-24, however, not only inhibited the protein expression of S100A8, TLR4, and MyD88 in lung tissues but also reduced the release of pro-inflammatory cytokines in the plasma and bronchoalveolar lavage fluid, thereby attenuating inflammatory responses and pathological injuries in the lung.

Conclusions: Our data suggest that miR-24 attenuates airway inflammatory responses in COPD by inhibiting the TLR4/MyD88 pathway via targeting S100A8.

Recent advances in cystic fibrosis (CF) treatments have led to improved survival, with life expectancy for Australians living with CF at 57yo. As life expectancy improves, long-term cardiovascular disease risk factors (as for the general population) will become an issue in these patients. We hypothesized that increased leukocyte expression of vasoconstriction and pro-fibrotic mediators may contribute to CF severity in adults with CF. We recruited 13 adult and 24 pediatric healthy controls, and 53 adults and 9 children living with CF. Leukocyte expression/release of endothelin-1 (ET1) and members of the TGF-β/Smad signaling were measured by multifluorescence quantitative confocal microscopy, Western blotting, ELISA, and real-time quantitative polymerase chain reaction. The association between plasma ET1 levels and lung function was assessed. Leukocytes from adults living with CF expressed higher ET1 levels (p = 0.0033), and TGF-β (p = 0.0031); the phosphorylation ratio increased for Smad2/3 (p = 0.0136) but decreased for Smad1/5/8 (p = 0.0007), vs. control subjects. Plasma ET1 levels were significantly increased in adults with CF with FEV₁<50% (p = 0.002) vs. controls, and adults with CF with normal lung function. The release of ET1 in adult plasma inversely correlated with CF severity (-0.609, p = 0.046). Our data indicates that upregulated ET1 and TGF-β/Smad signaling in leukocytes may contribute to CF severity, highlighting the need for further investigations into their impact on the clinical outcomes of people living with CF.

Purpose: In this study, we identified differentially expressed genes (DEGs) and signaling pathways to gain insight into the pathogenesis of acute lung injury (ALI). Methods: C57BL/6 mice were intravenously injected with lipopolysaccharide (LPS) to establish a sepsis-induced ALI model. Hematoxylin-eosin (H&E) and enzyme-linked immunosorbent assays (ELISAs) were used to evaluate the model. Whole transcriptome sequencing was performed to identify the expression changes in lncRNAs, circRNAs, miRNAs and mRNAs in lung tissues. The crucial RNAs and the biological function of the target genes were confirmed and annotated based on bioinformatics analysis. Real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was employed to verify the expression levels of key lncRNAs, circRNAs, miRNAs and mRNAs in the lung tissues and human bronchoalveolar lavage (BALF). Results: A total of 3304 (1632 upregulated and 1672 downregulated) differentially expressed mRNAs, 794 (397 up and 397 down) differentially expressed lncRNAs, 89 (58 up and 31 down) differentially expressed circRNAs, and 14 (11 up and 3 down) differentially expressed miRNAs were identified between the control and LPS lung tissues. The lncRNA ceRNA subnetwork and circRNA ceRNA subnetwork were constructed based on the observed interaction and co-expression among the differentially expressed RNAs. An analysis of the protein-protein interaction (PPI) network and hub genes revealed crucial mRNAs for circRNA-Tcf20. The lncRNA-Snhg12, Edn1, Stat1, miR-212-3p and miR-223-3p were upregulated in sepsis ARDS patients. CircRNA-Tcf20, Col1a1, Col1a2 and Flt3 were significantly downregulated in sepsis ARDS patients. The biological function analysis indicated that these genes were enriched in the TNF signaling pathway, Necroptosis signaling pathway and the PI3K-Akt signaling pathway. Conclusions: Our findings suggest that circRNA-Tcf20, miR-212-3p, miR-223-3p, Col1a1, Col1a2 and Flt3 may be new regulatory factors that participate in the pathogenesis of sepsis-related acute lung injury. CircRNA-Tcf20, lncRNA-Snhg12 and all the other RNAs may be potential biomarkers for septic ALI/ARDS.