ABSTRACT Chronic obstructive pulmonary disease (COPD) is characterized by progressive alveolar destruction and defective regeneration, yet the matrix‐derived factors contributing to this process remain poorly defined. We investigated the role of elastin‐derived peptides (EDPs), bioactive fragments generated during cigarette smoke (CS)‐induced elastin degradation, in alveolar epithelial dysfunction. In lung tissues from patients with COPD and in CS‐exposed mice, elevated levels of EDPs were associated with elastic fiber disruption and impaired alveolar type 2 (AT2)‐to‐alveolar type 1 (AT1) differentiation. These observations were supported by histological analyses, single‐cell transcriptomic profiling, and organoid‐based functional assays. In mouse and human alveolar organoids, CS extract and EDPs each suppressed organoid growth and impaired AT2‐to‐AT1 differentiation. Mechanistically, EDPs exposure was associated with activation of TLR4/NF‐κB signaling, and reduced β‐catenin activity, whereas pharmacological inhibition of TLR4 partially restored alveolar epithelial differentiation. Notably, the EDPs‐neutralizing agent TB partially rescued AT2‐to‐AT1 differentiation in organoids and alleviated emphysematous injury in vivo. Together, these findings identify EDPs as an important matrix‐derived mediator of alveolar regenerative failure in COPD and support further evaluation of EDP‐targeted intervention as a potential strategy for promoting alveolar repair.

Biomass-related airborne fine particulate matter (PM2.5) is an important risk factor for chronic obstructive pulmonary disease (COPD). Macrophage polarization has been reported to be involved in PM2.5-induced COPD, but the dynamic characteristics and underlying mechanism of this process remain unclear. Our study established a PM2.5-induced COPD mouse model and revealed that M2 macrophages predominantly presented after 4 and 6 months of PM2.5 exposure, during which a notable increase in MMP12 was observed. Single cell analysis of lung tissues from COPD patients and mice further revealed that M2 macrophages were the dominant macrophage subpopulation in COPD, with MMP12 being involved as a hub gene. In vitro experiments further demonstrated that PM2.5 induced M2 polarization and increased MMP12 expression. Moreover, we found that PM2.5 increased IL-4 expression, STAT6 phosphorylation and nuclear translocation. Nuclear pSTAT6 then bound to the MMP12 promoter region. Furthermore, the inhibition of STAT6 phosphorylation effectively abrogated the PM2.5-induced increase in MMP12. Using a coculture system, we observed a significantly reduced level of E-cadherin in alveolar epithelial cells cocultured with PM2.5-exposed macrophages, while the decrease in E-cadherin was reversed by the addition of an MMP12 inhibitor to the co-culture system. Taken together, these findings indicated that PM2.5 induced M2 macrophage polarization and MMP12 upregulation via the IL-4/STAT6 pathway, which resulted in alveolar epithelial barrier dysfunction and excessive extracellular matrix (ECM) degradation, and ultimately led to COPD progression. These findings may help to elucidate the role of macrophages in COPD, and suggest promising directions for potential therapeutic strategies.

Cold-chain environment could extend the survival duration of SARS-CoV-2 and increases the risk of transmission. However, the effect of clod-chain environmental factors and packaging materials on SARS-CoV-2 stability and the efficacy of intervention measures to inactivate SARS-CoV-2 under cold-chain environment remains uncertain. This study aimed to unravel cold-chain environmental factors that preserved the stability of SARS-CoV-2 and disinfection measures against SARS-CoV-2 under the cold-chain environment. The spike gene of SARS-CoV-2 isolated from Wuhan hu-1 was used to construct the SARS-CoV-2 pseudovirus and used as model of the SARS-CoV-2 virus. The decay rate of SARS-CoV-2 pseudovirus in the cold-chain environment, various types of packaging material surfaces i.e., PE plastic, stainless steel, Teflon and cardboard, and in frozen seawater was investigated. The influence of LED visible light(wavelength 450 nm-780 nm) and airflow movement on the stability of SARS-CoV-2 pseudovirus at -18° C were subsequently assessed. The results show that SARS-CoV-2 pseudovirus decayed more rapidly on porous cardboard surface compared with the non-porous surfaces including PE plastic, stainless steel and Teflon. Compared with 25° C, the decay rate of SARS-CoV-2 pseudovirus was significantly lower at low temperature. Seawater preserved viral stability both at -18° C and repeated freeze-thawing cycles compared with deionized water. LED visible light illumination and airflow movement environment at -18° C reduced the SARS-CoV-2 pseudovirus stability. In conclusion, our results indicate cold-chain temperature and seawater as risk factors for SARS-CoV-2 transmission and LED visible light illumination and airflow movement as possible disinfection measures of SARS-CoV-2 under the cold-chain environment.Importance It is widely recognized that low temperature is a condition for maintaining virus vitality, and cold-chain transportation spreads the events of the SARS-CoV-2 were reported. This study provides that the decay rate of the SARS-CoV-2 pseudovirus at low temperatures varies on different packaging materials, and salt ions present in frozen foods such as seafood may protect virus survival. These results provide evidence for the possibility of SARS-CoV-2 transmission through cold-chain transport and also suggest the importance for disinfection of items. However, the commonly used disinfection methods of ultraviolet radiation and chemical reagents are generally not suitable for the disinfection of frozen food. Our study shows LED visible light illumination and airflow movement as possible disinfection measures of SARS-CoV-2 under the cold-chain environment. This has implications for reducing the long-distance transmission of the virus through cold-chain transportation.

Background Particular matter 2.5 (PM2.5) is one of the most important air pollutant, and it is positively associated with the development of chronic obstructive pulmonary disease (COPD). However, the precise underlying mechanisms through which PM2.5 promotes the development of COPD remains largely unknown. Methods Mouse alveolar destruction were determined by histological analysis of lung tissues and lung function test. Alveolar type II cells (AT2) to alveolar type I cells (AT1) transition in PM2.5-induced COPD mouse model was confirmed via immunofluorescence staining and qPCR analysis. The differentially expressed genes in PM2.5-induced COPD mouse model were identified by RNA-sequencing of alveolar epithelial organoids and generated by bioinformatics analysis. Results In this study, we found that 6 months exposure of PM2.5 induced a significantly decreased pulmonary compliance and resulted in pulmonary emphysema in mice. We showed that PM2.5 exposure significantly reduced the AT2 to AT1 cell transition in vitro and in vivo. In addition, we found a reduced expression of the intermediate AT2-AT1 cell process marker claudin 4 (CLDN4) at day 4 of differentiation in mouse alveolar organoids treated with PM2.5, suggesting that PM2.5 exposure inhibited AT2 cells from entering the transdifferentiation process. RNA-sequencing of mouse alveolar organoids showed that several key signaling pathways that involved in the AT2 to AT1 cell transition were significantly altered including the Wnt signaling, MAPK signaling and signaling pathways regulating pluripotency of stem cells following PM2.5 exposure. Conclusions In summary, these data demonstrate a critical role of AT2 to AT1 cell transition in PM2.5-induced COPD mouse model and reveal the signaling pathways that potentially regulate AT2 to AT1 cell transition during this process. Our findings therefore advance the current knowledge of PM2.5-induced COPD and may lead to a novel therapeutic strategy to treat this disease.

Additional file 2. Alveolar differentiation phase RNA-seq, include RNA sequencing data of alveolar organoids in differentiation phase.

Fine particulate matter (PM2.5) exposure is a significant cause of chronic obstructive pulmonary disease (COPD), but the detailed mechanisms involved in COPD remain unclear. In this study, we established PM2.5-induced COPD rat models and showed that PM2.5 induced pulmonary microvascular injury via accelerating vascular endothelial apoptosis, increasing vascular permeability, and reducing angiogenesis, thereby contributing to COPD development. Moreover, microvascular injury in COPD was validated by measurements of plasma endothelial microparticles (EMPs) and serum VEGF in COPD patients. We then performed m6A sequencing, which confirmed that altered N6-methyladenosine (m6A) modification was induced by PM2.5 exposure. The results of a series of experiments demonstrated that the expression of methyltransferase-like protein 16 (METTL16), an m6A regulator, was upregulated in PM2.5-induced COPD rats, while the expression of other regulators did not differ upon PM2.5-induction. To clarify the regulatory effect of METTL16-mediated m6A modification induced by PM2.5 on pulmonary microvascular injury, cell apoptosis, permeability, and tube formation, the m6A level in METTL16-knockdown pulmonary microvascular endothelial cells (PMVECs) was evaluated, and the target genes of METTL16 were identified from a set of the differentially expressed and m6A-methylated genes associated with vascular injury and containing predicted sites of METTL16 methylation. The results showed that Sulfatase 2 (Sulf2) and Cytohesin-1 (Cyth1) containing the predicted METTL16 methylation sites, exhibited higher m6A methylation and were downregulated after PM2.5 exposure. Further studies demonstrated that METTL16 may regulate Sulf2 expression via m6A modification and thereby contribute to PM2.5-induced microvascular injury. These findings not only provide a better understanding of the role played by m6A modification in PM2.5-induced microvascular injury, but also identify a new therapeutic target for COPD.

Increased vascular endothelial permeability can disrupt vascular barrier function and further lead to multiple human diseases.Our previous reports indicated that particulate matter 2.5 (PM2.5)can enhance the permeability of vascular endothelial cells.However, the regulatory mechanism was not comprehensively demonstrated.Therefore, this work elucidated this mechanism by demonstrating that PM2.5 can increase the permeability of HUVECs by inhibiting the expression of Hickson compact group 18 (HCG18).Moreover, we demonstrated that lncRNA HCG18 functioned as a ceRNA for miR-21-5p and led to the derepression of its target SOX7, which could further transcriptionally activate the expression of VE-cadherin to regulate the permeability of HUVECs.In this study, we provide evidence that HCG18/miR-21-5p/SOX7/VE-cadherin signaling is involved in PM2.5-induced vascular endothelial barrier dysfunction.

OBJECTIVE:To determine the effect of andrographolide (Andro) on angiogenesis of human umbilical vein endothelial cells (HUVECs).
 Methods: HUVECs were treated with different concentrations of Andro and the cell viability was detected with Cell Counting Kit-8 (CCK-8). HUVECs were treated with half lethal dose (IC50) of Andro. Matrigel was used to make capillary formation of HUVECs and the effect of Andro on capillary formation was evaluated by calculating the percentage of capillary formation. Moreover, the effects of Andro and the supernatant from cultured A549 tumor cells on capillary formation were evaluated by calculating the percentage of capillary formation. The effect of Andro on the expression of matrix metalloproteinase-9 (MMP-9) was determined with Western blot.
 Results: The cell viability of HUVECs decreased with the increase of Andro concentrations. IC50 was 20 μmol/L. The capillary formation of HUVECs was inhibited when treated with 20 μmol/L Andro for 24 hours. Moreover, Andro was able to antagonize the promotion of the capillary formation induced by the supernatant from cultured tumor cells. Andro could suppress the expression of MMP-9 and antagonize the capillary formation.
 Conclusion: Andro inhibits the capillary formation of HUVECs and can antagonize the promotion of angiogenesis induced by the supernatant from cultured tumor cells.