Establishment and evaluation of an in vitro blast lung injury model using alveolar epithelial cells

Resveratrol alleviates blast lung injury by modulating the epithelial sodium channel (ENaC) via the PI3K/AKT pathway

Blast lung injury (BLI) is a major cause of death in blast injuries, largely due to pulmonary edema. Effective clearance of alveolar fluid is critical for resolving pulmonary edema, with the epithelial sodium channel (ENaC) playing a key role in this process. Resveratrol (RES), a natural compound with known antioxidant and anti-inflammatory properties, has shown promise in treating respiratory diseases. However, its potential protective effects against BLI, particularly through ENaC modulation, remain unclear. In this study, complementary in vivo and in vitro models were used to investigate mechanisms underlying pulmonary edema following a gas explosion. We discovered that RES significantly alleviated BLI by decreasing pulmonary edema, pulmonary index, W/D ratio, oxidative stress, inflammatory cell infiltration, and TNF-α and IL-1β expression levels in rat lung tissue. RES upregulated the expression of ENaC and PI3K/AKT both in rats and in A549 cells. The knockout of the PI3K-p85 gene suppressed RES-induced upregulation of p-AKT and ENaC, reversing protein expression in A549 cells. Altogether, RES shows potential to attenuate blast-induced lung injury by upregulating ENaC, partly through the PI3K/AKT signaling pathway. This study highlights RES as a potential therapeutic agent for BLI and offers new insights into its mechanisms of action.

Evaluating the effectiveness of handheld ultrasound in primary blast lung injury: a comprehensive study

The incidence of blast injuries has been rising globally, particularly affecting the lungs due to their vulnerability. Primary blast lung injury (PBLI) is associated with high morbidity and mortality rates, while early diagnostic methods are limited. With advancements in medical technology, and portable handheld ultrasound devices, the efficacy of ultrasound in detecting occult lung injuries early remains unclear. This study evaluates the effectiveness of immediate lung ultrasound in diagnosing PBLI. The study involved 25 healthy male Bama mini-pigs subjected to BST-I-type biological shock wave tubes. The pigs were randomly assigned to non-injured and injured groups with driving pressures of 4.0 MPa, 4.5 MPa, and 4.8 MPa. Four PBLI models were created: no injury, minor, moderate, serious and severe. Immediate lung ultrasound following the BLUE-PLUS protocol and arterial blood gas analysis were conducted pre-injury and 0.5 h, 3 h, 6 h, 12 h, and 24 h post-injury, respectively. The study analyzed lung ultrasound score differences and their correlations with lung function parameters, using ROC analysis to determine early diagnostic standards and mortality prediction efficacy. The study found that in cases of moderate and severe PBLI, lung ultrasound scores and AaDO2 significantly increased at 0.5 h post-injury, while PaO2 decreased. There was good consistency between left and right lung ultrasound results at all times. Lung ultrasound scores were significantly correlated with PaO2 and AaDO2 but not with PaCO2. The scores accurately predicted injury severity at various time points within 24 h post-injury, and the 0.5 h lung ultrasound score predicted 24 h mortality with 95.8% efficiency. PBLI exhibits hidden severity, necessitating improved early diagnostics. Immediate lung ultrasound provides effective differentiation for moderate and severe PBLI at multiple time points within 24 h post-injury, is easy to implement, and offers effective mortality risk prediction as early as 0.5 h post-injury. These findings underscore lung ultrasound's significant clinical application value in pre-hospital early treatment settings for PBLI.

Pathophysiological changes and injury markers for acute lung injury from blunt impact in infant rabbits

BACKGROUND

Traffic accidents, particularly blunt impacts, cause serious injuries in children. We aimed to assess inflammatory and injury responses in infant rabbits subjected to acute lung injury resulting from blunt impact, with the goal of identifying potential circulatory injury markers.

METHODS

Forty 4-week-old infant rabbits were subjected to a right chest impact using a Hopkinson bar with 2,600 g. Computed tomography was employed to assess injury severity. Pathological changes were observed using hematoxylin and eosin staining in the control, 0, 24, and 72 h groups, post-injury. Immunohistochemistry was used to examine surfactant protein A (SP-A) changes in right lung tissues and upper main bronchi. Serum levels of interleukin-6 (IL-6), IL-8, and SP-A were measured using ELISA within 24 h post-injury in the control, 0 h, and 24 h groups.

RESULTS

Following blunt injury, significant increases were observed in blood white blood cell count (F = 101.556, P < 0.01) and neutrophil percentage (F = 104.228, P < 0.01), which gradually decreased after 24 and 72 h. The lung wet/dry weight ratio indicated significant edema (F = 79.677, P < 0.01), corroborated by hematoxylin and eosin staining showing edema, exudation, and marked granulocyte infiltration in the control, 0 h, 24 h and 72 h groups. SP-A levels decreased rapidly at 0 h, and recovered between 24 and 72 h in the right lung tissues (F = 6.7, P < 0.05), left lung (F = 15.825, P < 0.05) and upper main bronchi (F = 59.552, P < 0.01). The ELISA results showed increasing trends for the control and 0 h groups, while decreasing trends were observed in 24 h group for IL-6 (F = 58.328, P < 0.01) and IL-8 (F = 41.802, P < 0.01). Conversely, SP-A exhibited a decreasing trend in the control and 0 h groups but increased in the serum of 24 h group (F = 52.629, P < 0.01).

DISCUSSION

In cases of direct chest trauma in infant rabbits, particularly mild injuries without rib fractures. SP-A levels correlated with pathological changes across all groups and may serve as biomarkers for pediatric blunt lung impact.

Esophageal pressure monitoring and its clinical significance in severe blast lung injury

Background

The incidence of blast lung injury (BLI) has been escalating annually due to military conflicts and industrial accidents. Currently, research into these injuries predominantly uses animal models. Despite the availability of various models, there remains a scarcity of studies focused on monitoring respiratory mechanics post-BLI. Consequently, our objective was to develop a model for monitoring esophageal pressure (Pes) following BLI using a biological shock tube (BST), aimed at providing immediate and precise monitoring of respiratory mechanics parameters post-injury.

Methods

Six pigs were subjected to BLI using a BST, during which Pes was monitored. We assessed vital signs; conducted blood gas analysis, hemodynamics evaluations, and lung ultrasound; and measured respiratory mechanics before and after the inflicted injury. Furthermore, the gross anatomy of the lungs 3 h post-injury was examined, and hematoxylin and eosin staining was conducted on the injured lung tissues for further analysis.

Results

The pressure in the experimental section of the BST reached 402.52 ± 17.95 KPa, with a peak pressure duration of 53.22 ± 1.69 ms. All six pigs exhibited an anatomical lung injury score ≥3, and pathology revealed classic signs of severe BLI. Post-injury vital signs showed an increase in HR and SI, along with a decrease in MAP (p < 0.05). Blood gas analyses indicated elevated levels of Lac, CO2-GAP, A-aDO2, HB, and HCT and reduced levels of DO2, OI, SaO2, and OER (p < 0.05). Hemodynamics and lung ultrasonography findings showed increased ELWI, PVPI, SVRI, and lung ultrasonography scores and decreased CI, SVI, GEDI, and ITBI (p < 0.05). Analysis of respiratory mechanics revealed increased Ppeak, Pplat, Driving P, MAP, PEF, Ri, lung elastance, MP, Ptp, Ppeak - Pplat, and ΔPes, while Cdyn, Cstat, and time constant were reduced (p < 0.05).

Conclusion

We have successfully developed a novel respiratory mechanics monitoring model for severe BLI. This model is reliable, repeatable, stable, effective, and user-friendly. Pes monitoring offers a non-invasive and straightforward alternative to blood gas analysis, facilitating early clinical decision-making. Our animal study lays the groundwork for the early diagnosis and management of severe BLI in clinical settings.

Thrombospondin-1-mediated crosstalk between autophagy and oxidative stress orchestrates repair of blast lung injury

Coal mining carries inherent risks of catastrophic gas explosions capable of inflicting severe lung injury. Using complementary in vivo and in vitro models, we explored mechanisms underlying alveolar epithelial damage and repair following a gas explosion in this study. In a rat model, the gas explosion was demonstrated to trigger inflammation and injury within the alveolar epithelium. The following scRNA-sequencing revealed that alveolar epithelial cells exhibited the most profound transcriptomic changes after gas explosion compared to other pulmonary cell types. In the L2 alveolar epithelial cells, the blast was found to cause autophagic flux by inducing autophagosome formation, LC3 lipidation, and p62 degradation. Transcriptomic profiling of the L2 cells identified PI3K-Akt and p53 pathways as critical modulators governing autophagic and oxidative stress responses to blast damage. Notably, Thrombospondin-1 (Thbs1) was determined for the first time as a pivotal node interconnecting these two pathways. The findings of this study illuminate intricate mechanisms of alveolar epithelial injury and recovery after blast trauma, highlighting autophagic and oxidative stress responses mediated by Thbs1-associated PI3K-Akt and p53 pathways as high-value therapeutic targets, and strategic modulation of these pathways in future studies may mitigate lung damage by reducing oxidative stress while engaging endogenous tissue repair processes like autophagy.

Age-related exacerbation of lung damage after trauma is associated with increased expression of inflammasome components

Background

Trauma, a significant global cause of mortality and disability, often leads to fractures and hemorrhagic shock, initiating an exaggerated inflammatory response, which harms distant organs, particularly the lungs. Elderly individuals are more vulnerable to immune dysregulation post-trauma, leading to heightened organ damage, infections, and poor health outcomes. This study investigates the role of NF-κB and inflammasomes in lung damage among aged mice post-trauma.

Methods

Twelve male C57BL/6J mice underwent hemorrhagic shock and a femoral fracture (osteotomy) with external fixation (Fx) (trauma/hemorrhage, THFx), while another 12 underwent sham procedures. Mice from young (17-26 weeks) and aged (64-72 weeks) groups (n=6) were included. After 24h, lung injury was assessed by hematoxylin-eosin staining, prosurfactant protein C (SPC) levels, HMGB1, and Muc5ac qRT-PCR. Gene expression of Nlrp3 and Il-1β, and protein levels of IL-6 and IL-1β in lung tissue and bronchoalveolar lavage fluid were determined. Levels of lung-infiltrating polymorphonuclear leukocytes (PMNL) and activated caspase-3 expression to assess apoptosis, as well as NLRP3, ASC, and Gasdermin D (GSDMD) to assess the expression of inflammasome components were analyzed via immunostaining. To investigate the role of NF-κB signaling, protein expression of phosphorylated and non-phosphorylated p50 were determined by western blot.

Results

Muc5ac, and SPC as lung protective proteins, significantly declined in THFx versus sham. THFx-aged exhibited significantly lower SPC and higher HMGB1 levels versus THFx-young. THFx significantly increased activated caspase-3 versus both sham groups, and THFx-aged had significantly more caspase-3 positive cells versus THFx-young. IL-6 significantly increased in both sham and THFx-aged groups versus corresponding young groups. THFx significantly enhanced PMNL in both groups versus corresponding sham groups. This increase was further heightened in THFx-aged versus THFx-young. Expression of p50 and phosphorylated p50 increased in all aged groups, and THFx-induced p50 phosphorylation significantly increased in THFx-aged versus THFx-young. THFx increased the expression of inflammasome markers IL-1β, NLRP3, ASC and GSDMD versus sham, and aging further amplified these changes significantly.

Conclusion

This study's findings suggest that the aging process exacerbates the excessive inflammatory response and damage to the lung following trauma. The underlying mechanisms are associated with enhanced activation of NF-κB and increased expression of inflammasome components.