Vaporization of perfluorocarbon attenuates sea-water-drowning-induced acute lung injury by deactivating the NLRP3 inflammasomes in canines.

Seawater-drowning-induced acute lung injury (SD-ALI) is a life-threatening disorder characterized by increased alveolar-capillary permeability, an excessive inflammatory response, and refractory hypoxemia. Perfluorocarbons (PFCs) are biocompatible compounds that are chemically and biologically inert and lack toxicity as oxygen carriers, which could reduce lung injury in vitro and in vivo. The aim of our study was to explore whether the vaporization of PFCs could reduce the severity of SD-ALI in canines and investigate the underlying mechanisms. Eighteen beagle dogs were randomly divided into three groups: the seawater drowning (SW), perfluorocarbon (PFC), and control groups. The dogs in the SW group were intratracheally administered seawater to establish the animal model. The dogs in the PFC group were treated with vaporized PFCs. Probe-based confocal laser endomicroscopy (pCLE) was performed at 3 h. The blood gas, volume air index (VAI), pathological changes, and wet-to-dry (W/D) lung tissue ratios were assessed. The expression of heme oxygenase-1 (HO-1), nuclear respiratory factor-1 (NRF1), and NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasomes was determined by means of quantitative real-time polymerase chain reaction (qRT-PCR) and immunological histological chemistry. The SW group showed higher lung injury scores and W/D ratios, and lower VAI compared to the control group, and treatment with PFCs could reverse the change of lung injury score, W/D ratio and VAI. PFCs deactivated NLRP3 inflammasomes and reduced the release of caspase-1, interleukin-1ß (IL-1ß), and interleukin-18 (IL-18) by enhancing the expression of HO-1 and NRF1. Our results suggest that the vaporization of PFCs could attenuate SD-ALI by deactivating NLRP3 inflammasomes via the HO-1/NRF1 pathway.

Coculture with bone marrow­derived mesenchymal stem cells attenuates inflammation and apoptosis in lipopolysaccharide­stimulated alveolar epithelial cells via enhanced secretion of keratinocyte growth factor and angiopoietin­1 modulating the Toll­like receptor­4 signal pathway.

Acute lung injury (ALI) is a common, costly and potentially lethal disease with characteristics of alveolar­capillary membrane disruption, pulmonary edema and impaired gas exchange due to increased apoptosis and pulmonary inflammation. There is no effective and specific therapy for ALI; however, mesenchymal stem cells (MSCs) have been demonstrated to be a potential option. Lipopolysaccharide (LPS) is a highly proinflammatory molecule that is used to mimic an in vivo inflammatory and damaged state in vitro. The present study investigated the effect of bone marrow­derived MSCs on an LPS­induced alveolar epithelial cell (A549 cell line) injury and its underlying mechanisms by a Transwell system. It was identified that a high LPS concentration caused a decrease in cell viability, increases in apoptosis, inflammatory cytokine release and NF­κB activity, disruption of the caspase­3/Bcl­2 ratio, upregulation of Toll­like receptor 4 (TLR4), myeloid differentiation factor 88 (MyD88) and toll­interleukin­1 receptor domain­containing adaptor inducing interferon (TRIF) expression, and facilitation of TLR4/MyD88 and TLR4/TRIF complex formation in A549 cells. Coculture with MSCs attenuated all of these activities induced by LPS in A549 cells. In addition, an increased level of keratinocyte growth factor (KGF) and angiopoietin­1 (ANGPT1) secretion from MSCs was observed under inflammatory stimulation. KGF and/or ANGPT1 neutralizing antibodies diminished the beneficial effect of MSC conditioned medium. These data suggest that MSCs alleviate inflammatory damage and cellular apoptosis induced by LPS in A549 cells by modulating TLR4 signals. These changes may be partly associated with an increased secretion of KGF and ANGPT1 from MSCs under inflammatory conditions. These data provide the basis for development of MSC­based therapies for ALI.

Paralemmin-3 contributes to lipopolysaccharide-induced inflammatory response and is involved in lipopolysaccharide-Toll-like receptor-4 signaling in alveolar macrophages.

Alveolar macrophages (AMs) are the first line of defense against foreign stimulation in alveoli, and they participate in inflammatory responses during acute lung injury (ALI). Previous studies indicated that paralemmin-3 (PALM3) expression is induced by lipopolysaccharides (LPS) and may be involved in LPS-Toll-like receptor 4 (TLR4) signaling in alveolar epithelial cells. The aim of the present study was to investigate the effect of PALM3 on LPS-induced inflammation and its underlying mechanisms in rat AMs. For this purpose, the authors detected the expression of PALM3 in AMs by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting following LPS stimulation. Following this, a recombinant adenovirus expressing short hairpin RNA (shRNA) for PALM3 was constructed, as well as a recombinant adenovirus carrying the rat PALM3 gene to modulate the expression of PALM3 in rat AMs. At 48 h after transfection, the PALM3 expression in AMs was detected by RT-qPCR and western blotting. The levels of several cytokines and the activity of nuclear factor-κB and interferon regulatory factor 3 in AMs were measured after LPS stimulation. The localization of PALM3 and LPS-TLR4 signaling adaptor molecules in AMs was analyzed by confocal microscopy, and the physical interactions of PALM3 with these adaptors were assessed by co-immunoprecipitation assays. LPS induced PALM3 expression in AMs and that PALM3 expression promoted the LPS-induced inflammatory response, while PALM3 downregulation suppressed the LPS-induced inflammatory response in AMs. In addition, the results demonstrated that PALM3 could interact with TLR4, myeloid differentiation factor 88, interleukin (IL)-1 receptor associated kinase-1, tumor necrosis factor receptor associated factor-6, and Toll-IL-1 receptor containing adapter molecule-2 in AMs after LPS stimulation. These results suggested that PALM3 contributes to the LPS-induced inflammatory response and participates in LPS-TLR4 signaling in AMs. These data may provide the basis for the development of novel targeted therapeutic strategies of treating ALI.

[Experimental treatment of acute lung injury caused by inundation of thoracic cavity by seawater following open chest wound].

OBJECTIVE: To study the effects of lung protective ventilation and pentoxifylline (PTX) on acute lung injury (ALI) caused by open chest wound with seawater inundation of the thoracic cavity. METHODS: A model of ALI caused by open chest wound and seawater inundation of thoracic cavity was reproduced in dogs. Twenty-four healthy dogs were randomly divided into four groups: no-treatment group (group A), ordinary treatment group (group B), lung protective ventilation treatment group (group C), and lung protective ventilation and PTX treatment group (group D). The parameters of hemodynamics, arterial blood gas analysis, plasma osmotic pressure and serum electrolytes in dogs were determined at 0 and 6 hours after injury and at 2 and 4 hours after treatment. Blood samples and bronchoalveolar lavage fluid (BALF) were collected to assess the changes in cytokines including tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and IL-8. RESULTS: The arterial oxygen partial pressure (PaO(2)) and oxygenation index (PaO(2)/FiO(2)) in group B were still lower than normal values at 2 and 4 hours after treatment, but those parameters in group C and group D distinctly recovered. The parameters of hemodynamics, plasma osmotic pressure and serum electrolytes were all normalized in group B, C and D at 2 and 4 hours after treatment compared with those in group A. The levels of TNF-alpha in peripheral blood in group C and the TNF-alpha and IL-8 levels in peripheral blood and IL-6, IL-8 levels in BALF in group D were significantly lower than those in group A and group B after treatment. The TNF-alpha in peripheral blood and IL-8 levels in BALF in group D were also significantly lower than those in group C after treatment. CONCLUSION: Lung protective ventilation is an effective method in the treatment of ALI caused by open chest wound with inundation of seawater in thoracic cavity. PTX can inhibit inflammatory reaction in the lung and peripheral blood.