PIM1 inhibition attenuated endotoxin-induced acute lung injury through modulating ELK3/ICAM1 axis on pulmonary microvascular endothelial cells

Early Progression of Abdominal Aortic Aneurysm is Decelerated by Improved Endothelial Barrier Function via ALDH2-LIN28B-ELK3 Signaling

The involvement of endothelial barrier function in abdominal aortic aneurysm (AAA) and its upstream regulators remains unknown. Single-cell RNA sequencing shows that disrupted endothelial focal junction is an early (3 days) and persistent (28 days) event during Angiotensin II (Ang II)-induced AAA progression. Consistently, mRNA sequencing on human aortic dissection tissues confirmed downregulated expression of endothelial barrier-related genes. Aldehyde dehydrogenase 2 (ALDH2), a negative regulator of AAA, is found to be upregulated in the intimal media of AAA samples, leading to testing its role in early-stage AAA. ALDH2 knockdown/knockout specifically in endothelial cells (ECs) significantly increases expression of EC barrier markers related to focal adhesion and tight junction, restores endothelial barrier integrity, and suppresses early aortic dilation of AAA (7 and 14 days post-Ang II). Mechanically, ELK3 acts as an ALDH2 downstream regulator for endothelial barrier function preservation. At the molecular level, ALDH2 directly binds to LIN28B, a regulator of ELK3 mRNA stability, hindering LIN28B binding to ELK3 mRNA, thereby depressing ELK3 expression and impairing endothelial barrier function. Therefore, preserving vascular endothelial barrier integrity via ALDH2-specific knockdown in ECs holds therapeutic potential in the early management of AAAs.

Ferrostatin-1 Ameliorated Oxidative Lipid Damage in LPS-induced Acute Lung Injury

INTRODUCTION

Ferroptosis is a new type of regulated cell death that is characterized by the overwhelming iron-dependent accumulation of lethal lipid reactive oxygen species and is involved in various diseases. However, the relationship between ferroptosis and lipopolysaccharide (LPS)-induced acute lung injury (ALI) remains largely unknown.

METHODS

In this study, iron metabolism and ferroptosis-related gene mRNA levels in the lung tissues of LPS-induced ALI mice at different time points were detected. Then, the histological, cytokines production, and iron levels of LPS-induced ALI mice with or without the pretreatment of the ferroptosis inhibitor ferrostatin-1 (Fer-1) were measured after mice received the ferroptosis inhibitor ferrostatin-1 (Fer-1) intraperitoneally before LPS administration. Ferroptosis-related protein (GPX4, NRF2, and DPP4) expression was measured in the in vivo and in vitro ALI model. Finally, ROS accumulation and lipid peroxidation was measured in in vivo and in vitro study.

RESULTS

Our results showed that iron metabolism and ferroptosis-related gene mRNA demonstrated significant variation in LPS-treated pulmonary tissues. The ferroptosis inhibitor Fer-1 markedly attenuated the histologic injuries of the lung tissue and suppressed the production of cytokines in bronchoalveolar lavage fluid (BALF). Fer-1 administration reduced the levels of NRF2 and DPP4 protein induced by the LPS challenge. Furthermore, Fer-1 reversed the tendency of iron metabolism, MDA, SOD, and GSH levels induced by LPS administration in in vivo and in vitro.

CONCLUSIONS

Taken together, ferroptosis inhibition by ferrostatin-1 alleviated acute lung injury through modulating oxidative lipid damages induced by the LPS challenge.

Shared metabolic shifts in endothelial cells in stroke and Alzheimer's disease revealed by integrated analysis

Since metabolic dysregulation is a hallmark of both stroke and Alzheimer's disease (AD), mining shared metabolic patterns in these diseases will help to identify their possible pathogenic mechanisms and potential intervention targets. However, a systematic integration analysis of the metabolic networks of the these diseases is still lacking. In this study, we integrated single-cell RNA sequencing datasets of ischemic stroke (IS), hemorrhagic stroke (HS) and AD models to construct metabolic flux profiles at the single-cell level. We discovered that the three disorders cause shared metabolic shifts in endothelial cells. These altered metabolic modules were mainly enriched in the transporter-related pathways and were predicted to potentially lead to a decrease in metabolites such as pyruvate and fumarate. We further found that Lef1, Elk3 and Fosl1 may be upstream transcriptional regulators causing metabolic shifts and may be possible targets for interventions that halt the course of neurodegeneration.

Targeting macrophagic PIM-1 alleviates osteoarthritis by inhibiting NLRP3 inflammasome activation via suppressing mitochondrial ROS/Cl- efflux signaling pathway

BACKGROUND

Osteoarthritis (OA), in which macrophage-driven synovitis is considered closely related to cartilage destruction and could occur at any stage, is an inflammatory arthritis. However, there are no effective targets to cure the progression of OA. The NOD-, LRR-,and pyrin domain-containing protein 3 (NLRP3) inflammasome in synovial macrophages participates in the pathological inflammatory process and treatment strategies targeting it are considered to be an effective approach for OA. PIM-1 kinase, as a downstream effector of many cytokine signaling pathways, plays a pro-inflammatory role in inflammatory disease.

METHODS

In this study, we evaluated the expression of the PIM-1 and the infiltration of synovial macrophages in the human OA synovium. The effects and mechanism of PIM-1 were investigated in mice and human macrophages stimulated by lipopolysaccharide (LPS) and different agonists such as nigericin, ATP, Monosodium urate (MSU), and Aluminum salt (Alum). The protective effects on chondrocytes were assessed by a modified co-culture system induced by macrophage condition medium (CM). The therapeutic effect in vivo was confirmed by the medial meniscus (DMM)-induced OA in mice.

RESULTS

The expression of PIM-1 was increased in the human OA synovium which was accompanied by the infiltration of synovial macrophages. In vitro experiments, suppression of PIM-1 by SMI-4a, a specific inhibitor, rapidly inhibited the NLRP3 inflammasome activation in mice and human macrophages and gasdermin-D (GSDME)-mediated pyroptosis. Furthermore, PIM-1 inhibition specifically blocked the apoptosis-associated speck-like protein containing a CARD (ASC) oligomerization in the assembly stage. Mechanistically, PIM-1 inhibition alleviated the mitochondrial reactive oxygen species (ROS)/chloride intracellular channel proteins (CLICs)-dependent Cl- efflux signaling pathway, which eventually resulted in the blockade of the ASC oligomerization and NLRP3 inflammasome activation. Furthermore, PIM-1 suppression showed chondroprotective effects in the modified co-culture system. Finally, SMI-4a significantly suppressed the expression of PIM-1 in the synovium and reduced the synovitis scores and the Osteoarthritis Research Society International (OARSI) score in the DMM-induced OA model.

CONCLUSIONS

Therefore, PIM-1 represented a new class of promising targets as a treatment of OA to target these mechanisms in macrophages and widened the road to therapeutic strategies for OA.

SIRT6 attenuates LPS‐induced inflammation and apoptosis of lung epithelial cells in acute lung injury through ACE2/STAT3/PIM1 signaling

Background

Acute lung injury (ALI) is a severe and fatal respiratory disease. SIRT6 exerts pivotal activities in the process of lung diseases, but whether SIRT6 impacts ALI has not been covered.

Methods

Lentivirus recombinant expressing vector SIRT6 gene (Lent‐SIRT6) was constructed in mice, and there were control, lipopolysaccharide (LPS), LPS + Vehicle, and LPS + Lent SIRT6 groups. RT‐qPCR and western blot detected SIRT6 expression in lung tissues. HE staining observed pathological alternations in lung tissues. Wet‐to‐dry ratio of the lungs was then measured. The cell count of bronchoalveolar lavage fluid (BALF) was evaluated. Serum inflammation was examined with enzyme‐linked immunosorbent assay, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and western blot were to measure apoptosis. Western blot tested the expression of ACE2/STAT3/PIM1 signaling‐associated factors. At the cellular level, LPS was used to induce lung epithelial cells BEAS‐2B to establish cell injury models. SIRT6 was overexpressed and ACE2 expression was inhibited by cell transfection, and the mechanism of SIRT6 in LPS‐induced lung injury model was further explored by Cell Counting Kit‐8 (CCK‐8), western blot, quantitative reverse‐transcription polymerase chain reaction, TUNEL, and other techniques.

Results

The results of animal experiments showed that SIRT6 overexpression could reduce LPS‐induced lung pathological injury, pulmonary edema, and BALF cell ratio and attenuate LPS‐induced inflammatory response and cell apoptosis. In the above process, ACE2, STAT3, p‐STAT3, and PIM1 expression were affected. In cell experiments, SIRT6 expression was reduced in LPS‐induced BEAS‐2B cells. Inhibition of ACE2 expression could reverse the inhibitory effect of SIRT6 overexpression on ACE2/STAT3/PIM1 pathway, and cellular inflammatory response and apoptosis.

Conclusion

SIRT6 eased LPS‐evoked inflammation and apoptosis of lung epithelial cells in ALI through ACE2/STAT3/PIM1 signaling.

Heterogeneity of T cells and macrophages in chlorine-induced acute lung injury in mice using single-cell RNA sequencing

OBJECTIVE

Chlorine (Cl₂), as an asphyxiant toxicant, induced poisoning incidents and acute lung injury (ALI) occur frequently. The specific pathogenesis of Cl₂-induced ALI remains unclear. Immune cells play an important role in the process of lung damage. We used single-cell RNA sequencing (scRNA-seq) technology to explore T cells and macrophages molecular mechanism.

METHODS

Female BALB/c mice were exposed to 400 ppm Cl₂ for 15 min. scRNA-seq technology was used to observe the heterogeneity of T cells and macrophages. Hematoxylin-eosin (H&E) staining was used to evaluate the degree of lung injury. Immunofluorescence was used to verify the highly expressed genes of our interest.

RESULTS

A total of 5316 to 7742 cells were classified into eight different cell types. Several new highly expressed anti-inflammatory and pro-inflammatory genes were found in T cells and macrophages, which were further verified in vitro. Through the pseudotime analysis of macrophages, it was found that the expression of pro-inflammatory and anti-inflammatory genes showed opposite trends in the development of Cl₂-induced ALI. This study also mapped T cells-macrophage communication and identified the development of several important receptor-ligand complexes in Cl₂-induced ALI.

CONCLUSIONS

These findings are worthy of further exploration and provide new resources and directions for the study of Cl₂-induced ALI in mice, especially in immune and inflammation mechanisms.

Analysis of the risk factors for severe lung injury after radical surgery for tetralogy of fallot

Objective

This study aimed to determine the risk factors for severe lung injury (SLI) (partial pressure of oxygen/fraction of inspired oxygen <150) after radical surgery for tetralogy of Fallot with pulmonary stenosis (TOF/PS) in children.

Method

A retrospective analysis was conducted including a total of 287 children with TOF/PS aged below 10 years (including 166 males) who had undergone radical surgery at the Center of Pediatric Heart Disease of the Beijing Anzhen Hospital (China) from 2018 to 2020.

Results

A total of 83 cases (28.9%) had SLI after surgery. Univariate analysis showed that age, weight, pulmonary artery index (PAI), cardiopulmonary bypass (CPB) time, and polymorphonuclear leukocyte (PMN) percentage on the first day after surgery were risk factors for postoperative SLI. Multivariate logistic regression analysis showed that PAI, PMN percentage on the first day postoperatively, and CPB time were independent risk factors for SLI after surgery. The prediction model was established as follows: Logit(P) = 2.236 + 0.009*CPB-0.008*PAI-0.035*PMN, area under the curve (AUC) = 0.683, P < 0.001, sensitivity 65.8%, and specificity 68.6%. Following surgery, static lung compliance was significantly lower in the SLI group compared with the routine group. Complication rates and mortality were significantly higher in the SLI than in the routine group. Ventilator support times, the length of intensive care unit stays, and the total lengths of hospital stay were significantly longer in the SLI than in the routine group.

Conclusion

The occurrence of SLI following radical surgery for TOF in children significantly affected postoperative recovery, and PAI, PMN percentage on the first day postoperatively, and CPB time were independent risk factors for SLI.

Dexmedetomidine protects against acute lung injury in mice via the DUSP1/MAPK/NF-κB axis by inhibiting miR-152-3p

OBJECTIVE

Acute lung injury (ALI) is a debilitating condition in clinics. Dexmedetomidine (Dex) is known for its anti-apoptotic and anti-inflammatory properties. This study attempted to investigate the protective mechanism of Dex in ALI mice.

METHODS

Mice were pretreated with Dex before model establishment by tracheal injection of lipopolysaccharide (LPS). Pulmonary function indexes and wet-to-dry (W/D) ratio were measured. Pulmonary pathological changes were observed through HE staining, CD31+-positive mouse pulmonary microvascular endothelial cells (MPMVECs) were counted through immunofluorescence staining, and apoptosis was detected through TUNEL staining. miR-152-3p mimic, sh-DUSP1, or p38 MAPK inhibitor was delivered into MPMVECs, followed by combined treatment of Dex and LPS. miR-152-3p expression, apoptosis, levels of apoptosis- and MAPK/NF-κB pathway-associated proteins, and inflammatory factors were measured through RT-qPCR, flow cytometry, Western blot, and ELISA. The binding relationship of miR-152-3p and DUSP1 was verified through bioinformatics software and dual-luciferase assay. ALI mouse model was established after injection of miR-152-3p antagomir.

RESULTS

Dex improved ALI mouse pulmonary function and mitigated injury in mice and MPMVECs. miR-125-3p overexpression or sh-DUSP1 partially abolished the protection of Dex on MPMVECs. miR-152-3p targeted DUSP1. sh-DUSP1 partially averted the protection of Dex on MPMVECs. Dex inhibited the activation of the MAPK/NF-κB pathway in MPMVECs mediated by LPS, which was partially reversed by sh-DUSP1. The p38 MAPK inhibitor SB203580 antagonized the protective effect of Dex on MPMVECs mediated by sh-DUSP1. Similarly, downregulation of miR-152-3p mitigated ALI via the DUSP1/MAPK/NF-κB axis in vivo.

CONCLUSION

Dex relieved ALI in mice via the DUSP1/MAPK/NF-κB axis by down-regulating miR-152-3p.

Kindlin-2 Mediates Lipopolysaccharide-Induced Acute Lung Injury Partially via Pyroptosis in Mice

Acute lung injury (ALI) is characteristic of the wholesale destruction of the lung endothelial barrier, which results in protein-rich lung edema, influx of pro-inflammatory leukocytes, and intractable hypoxemia, contributing to high mortality. Kindlin-2 is involved in the process of tumor- and wound healing-associated inflammation. However, the effects of kindlin-2 on lipopolysaccharide (LPS)-induced ALI and its mechanisms remain unknown. In this study, we found that the concentration of kindlin-2 was elevated in the lungs of ALI mice. The specific deletion of kindlin-2 by kindlin-2 siRNA attenuated the severity of lung injury, which was demonstrated by the reduced number of pro-inflammatory cells in bronchoalveolar lavage fluid and lung wet/dry weight ratio, and ameliorated pathologic changes in the lungs of ALI mice. Furthermore, kindlin-2 siRNA decreased the mRNA levels of pro-inflammatory factors (IL-1β, IL-6, and TNF-α) and the protein levels of pyroptosis-related proteins. In vitro studies confirmed that LPS + ATP promoted the expressions of pro-inflammatory factors and pyroptosis-related proteins, which was prevented by kindlin-2 siRNA pretreatment in endothelial cells (ECs). In conclusion, inhibition of kindlin-2 developes protective effects against LPS-induced ALI and the cytotoxicity of ECs, which may depend on blocking pyroptosis.