A novel animal model of primary blast lung injury and its pathological changes in mice

Dynamic pathophysiological features of early primary blast lung injury: a novel functional incapacity pig model

INTRODUCTION

While there is evidence supporting the use of ultrasound for real-time monitoring of primary blast lung injury (PBLI), uncertainties remain regarding the timely detection of early PBLI and the limited data correlating it with commonly used clinical parameters. Our objective is to develop a functional incapacity model for PBLI that better addresses practical needs and to verify the early diagnostic effectiveness of lung ultrasound in identifying PBLI.

METHODS

We selected six healthy male pigs to develop an animal model using a bio-shock tube (BST-I). The injuries were induced at a pressure of 4.8 MPa. We monitored the animals before and after the injury using various methods to detect changes in vital signs, lung function, and hemodynamics.

RESULTS

The experimental peak overpressure was measured at 405.89 ± 4.14KPa, with the duration of the first positive peak pressure being 50.01ms. The mortality rate six hours after injury was 50%. The average Military Combat Injury Scale was higher than 3. Significant increases were observed in heart rate (HR), shock index (SI), alveolar-arterial oxygen gradient (AaDO2), lung ultrasound scores(LUS), and pulmonary vascular permeability index (PVPI) at 0.5 h, 3 h, and 6 h after-injury (p < 0.05). Conversely, there were notable decreases in average arterial pressure(MAP), oxygenation index (OI), stroke volume per heartbeat(SV), cardiac output power index(CPI), global end-diastolic index (GEDI), and intrathoracic blood volume index (ITBI) during the same time periods (p < 0.05). Meanwhile, the extrapulmonary water index (ELWI) showed a significant increase at 0.5 h and 6 h after injury (p < 0.05). At 6 h after injury, pulmonary ultrasound scores were positively correlated with HR (R = 0.731, p < 0.001), AaDO2 (R = 0.612, p = 0.012), SI (R = 0.661, p = 0.004), ELWI (R = 0.811, p < 0.001), PVPI (R = 0.705, p = 0.002). In contrast, these scores were negatively correlated with SpO2 (R = -0.583, p = 0.007),OI (R = -0.772, p < 0.001), ITBI (R = -0.637, p = 0.006).

CONCLUSION

We have successfully developed a novel, and highly reproducible animal model for assessing serious PBLI functional incapacity. This model displays immediate symptoms of hypoxia, decreased cardiac output, decreased blood volume, and abnormal lung ultrasound findings within 0.5 h of injury, with syptoms lasting for up to 6 h. Lung ultrasound evaluation is crucial for the early assessment of injuries, and is comparable to commonly used clinical parameters.

Shock wave damage from the ventral side in primary blast injury: An experimental study in pigs

AIM/PURPOSE

This study aimed to apply a shock wave from the ventral side of a pig and examine its effect to use the results for new body armor production for humans.

METHODS

Seven male hybrid pigs were used. Each pig was placed under general anesthesia on the experimental table in a blast tube in the left lateral position to expose the front chest area, and shock waves generated by compressed air at 3.0 MPa were applied. We examined changes in vital signs and arterial blood gas in the hyper-acute phase and computed tomography (CT) images, and autopsies were performed for organ damage after 3 h of observation. Pathological examination was performed for lung damage, which is considered a characteristic of shock wave injury.

RESULTS

All seven pigs survived. Respiratory arrest occurred in two pigs; however, spontaneous breathing resumed promptly afterward. Hypotension occurred at a frequency of 4. No bradycardia or cardiac arrest was observed in any pig. In the arterial blood gas analysis before and immediately after shock wave exposure and 1 h later, PaO2 decreased immediately but tended to improve thereafter. CT revealed pulmonary contusions and multiple bulla-like lesions on the surface of the lungs. An autopsy showed lung injury in all pigs, particularly in five cases with bulla-like lesions of various sizes on the lung surface across all lobes. Pathological findings showed visceral pleural detachment with elastic fibers from the lung parenchyma, and the cavity lesion on the lung surface comprised bullae. The degree of intra-abdominal hemorrhage varied; however, all but one case showed splenic injury.

CONCLUSION

None of the pigs exposed to shock waves from the ventral side died; however, most showed multiple bullae on the lung surface with lung contusion and splenic injury, which may have been greater than those exposed from the dorsal side. This may be due to the direct impact of the shock wave proceeding from the epigastrium and subcostal region, which are not protected by the skeletal structure of the thorax. These characteristics should be considered when producing new body armor for humans to protect the body from shock waves.

Anthrahydroquinone‑2,6‑disulfonate attenuates PQ‑induced acute lung injury through decreasing pulmonary microvascular permeability via inhibition of the PI3K/AKT/eNOS pathway

In paraquat (PQ)‑induced acute lung injury (ALI)/ acute respiratory distress syndrome, PQ disrupts endothelial cell function and vascular integrity, which leads to increased pulmonary leakage. Anthrahydroquinone‑2,6‑disulfonate (AH2QDS) is a reducing agent that attenuates the extent of renal injury and improves survival in PQ‑intoxicated Sprague‑Dawley (SD) rats. The present study aimed to explore the beneficial role of AH2QDS in PQ‑induced ALI and its related mechanisms. A PQ‑intoxicated ALI model was established using PQ gavage in SD rats. Human pulmonary microvascular endothelial cells (HPMECs) were challenged with PQ. Superoxide dismutase, malondialdehyde, reactive oxygen species and nitric oxide (NO) fluorescence were examined to detect the level of oxidative stress in HPMECs. The levels of TNF‑α, IL‑1β and IL‑6 were assessed using an ELISA. Transwell and Cell Counting Kit‑8 assays were performed to detect the migration and proliferation of the cells. The pathological changes in lung tissues and blood vessels were examined by haematoxylin and eosin staining. Evans blue staining was used to detect pulmonary microvascular permeability. Western blotting was performed to detect target protein levels. Immunofluorescence and immunohistochemical staining were used to detect the expression levels of target proteins in HPMECs and lung tissues. AH2QDS inhibited inflammatory responses in lung tissues and HPMECs, and promoted the proliferation and migration of HPMECs. In addition, AH2QDS reduced pulmonary microvascular permeability by upregulating the levels of vascular endothelial‑cadherin, zonula occludens‑1 and CD31, thereby attenuating pathological changes in the lungs in rats. Finally, these effects may be related to the suppression of the phosphatidylinositol‑3‑kinase (PI3K)/protein kinase B (AKT)/endothelial‑type NO synthase (eNOS) signalling pathway in endothelial cells. In conclusion, AH2QDS ameliorated PQ‑induced ALI by improving alveolar endothelial barrier disruption via modulation of the PI3K/AKT/eNOS signalling pathway, which may be an effective candidate for the treatment of PQ‑induced ALI.

The Neurovascular Unit as a Locus of Injury in Low-Level Blast-Induced Neurotrauma

Blast-induced neurotrauma has received much attention over the past decade. Vascular injury occurs early following blast exposure. Indeed, in animal models that approximate human mild traumatic brain injury or subclinical blast exposure, vascular pathology can occur in the presence of a normal neuropil, suggesting that the vasculature is particularly vulnerable. Brain endothelial cells and their supporting glial and neuronal elements constitute a neurovascular unit (NVU). Blast injury disrupts gliovascular and neurovascular connections in addition to damaging endothelial cells, basal laminae, smooth muscle cells, and pericytes as well as causing extracellular matrix reorganization. Perivascular pathology becomes associated with phospho-tau accumulation and chronic perivascular inflammation. Disruption of the NVU should impact activity-dependent regulation of cerebral blood flow, blood-brain barrier permeability, and glymphatic flow. Here, we review work in an animal model of low-level blast injury that we have been studying for over a decade. We review work supporting the NVU as a locus of low-level blast injury. We integrate our findings with those from other laboratories studying similar models that collectively suggest that damage to astrocytes and other perivascular cells as well as chronic immune activation play a role in the persistent neurobehavioral changes that follow blast injury.

Identification of potentially functional circRNAs and prediction of the circRNA-miRNA-hub gene network in mice with primary blast lung injury

OBJECTIVES

Primary blast lung injury (PBLI) is the main cause of death in blast injury patients, and is often ignored due to the absence of a specific diagnosis. Circular RNAs (circRNAs) are becoming recognized as new regulators of various diseases, but the role of circRNAs in PBLI remain largely unknown. This study aimed to investigate PBLI-related circRNAs and their probable roles as new regulators in PBLI in order to provide new ideas for PBLI diagnosis and treatment.

METHODS

The differentially expressed (DE) circRNA and mRNA profiles were screened by transcriptome high-throughput sequencing and validated by quantitative real-time PCR (qRT-PCR). The GO and KEGG pathway enrichment was used to investigate the potential function of DE mRNAs. The interactions between proteins were analyzed using the STRING database and hub genes were identified using the MCODE plugin. Then, Cytoscape software was used to illustrate the circRNA-miRNA-hub gene network.

RESULTS

A total of 117 circRNAs and 681 mRNAs were aberrantly expressed in PBLI, including 64 up-regulated and 53 down-regulated circRNAs, and 315 up-regulated and 366 down-regulated mRNAs. GO and KEGG analysis revealed that the DE mRNAs might be involved in the TNF signaling pathway and Fanconi anemia pathway. Hub genes, including Cenpf, Ndc80, Cdk1, Aurkb, Ttk, Aspm, Ccnb1, Kif11, Bub1 and Top2a, were obtained using the MCODE plugin. The network consist of 6 circRNAs (chr18:21008725-21020999 + , chr4:44893533-44895989 + , chr4:56899026-56910247-, chr5:123709382-123719528-, chr9:108528589-108544977 + and chr15:93452117-93465245 +), 7 miRNAs (mmu-miR-3058-5p, mmu-miR-3063-5p, mmu-miR-668-5p, mmu-miR-7038-3p, mmu-miR-761, mmu-miR-7673-5p and mmu-miR-9-5p) and 6 mRNAs (Aspm, Aurkb, Bub1, Cdk1, Cenpf and Top2a).

CONCLUSIONS

This study examined a circRNA-miRNA-hub gene regulatory network associated with PBLI and explored the potential functions of circRNAs in the network for the first time. Six circRNAs in the circRNA-miRNA-hub gene regulatory network, including chr18:21008725-21020999 + , chr4:44893533-44895989 + , chr4:56899026-56910247-, chr5:123709382-123719528-, chr9:108528589-108544977 + and chr15:93452117-93465245 + may play an essential role in PBLI.

Crosstalk between Inflammation and Hemorrhage/Coagulation Disorders in Primary Blast Lung Injury

Primary blast lung injury (PBLI), caused by exposure to high-intensity pressure waves from explosions in war, terrorist attacks, industrial production, and life explosions, is associated with pulmonary parenchymal tissue injury and severe ventilation insufficiency. PBLI patients, characterized by diffused intra-alveolar destruction, including hemorrhage and inflammation, might deteriorate into acute respiratory distress syndrome (ARDS) with high mortality. However, due to the absence of guidelines about PBLI, emergency doctors and rescue teams treating PBLI patients rely on experience. The goal of this review is to summarize the mechanisms of PBLI and their cross-linkages, exploring potential diagnostic and therapeutic targets of PBLI. We summarize the pathophysiological performance and pharmacotherapy principles of PBLI. In particular, we emphasize the crosstalk between hemorrhage and inflammation, as well as coagulation, and we propose early control of hemorrhage as the main treatment of PBLI. We also summarize several available therapy methods, including some novel internal hemostatic nanoparticles to prevent the vicious circle of inflammation and coagulation disorders. We hope that this review can provide information about the mechanisms, diagnosis, and treatment of PBLI for all interested investigators.

ROLE OF PEPTIDYLARGININE DEIMINASE AND NEUTROPHIL EXTRACELLULAR TRAPS IN INJURIES: FUTURE NOVEL DIAGNOSTICS AND THERAPEUTIC TARGETS

ABSTRACT

Injuries lead to an early systemic inflammatory state with innate immune system activation. Neutrophil extracellular traps (NETs) are a complex of chromatin and proteins released from the activated neutrophils. Although initially described as a response to bacterial infections, NETs have also been identified in the sterile postinjury inflammatory state. Peptidylarginine deiminases (PADs) are a group of isoenzymes that catalyze the conversion of arginine to citrulline, termed citrullination or deimination. PAD2 and PAD4 have been demonstrated to play a role in NET formation through citrullinated histone 3. PAD2 and PAD4 have a variety of substrates with variable organ distribution. Preclinical and clinical studies have evaluated the role of PADs and NETs in major trauma, hemorrhage, burns, and traumatic brain injury. Neutrophil extracellular trap formation and PAD activation have been shown to contribute to the postinjury inflammatory state leading to a detrimental effect on organ systems. This review describes our current understanding of the role of PAD and NET formation following injury and burn. This is a new field of study, and the emerging data appear promising for the future development of targeted biomarkers and therapies in trauma.