Year in review 2013: Acute lung injury, interstitial lung diseases, sleep and physiology

Fuzhengjiedu formula exerts protective effect against LPS-induced acute lung injury via gut-lung axis

BACKGROUND

Acute lung injury (ALI) is distinguished by rapid and severe respiratory distress and prolonged hypoxemia. A traditional Chinese medicine (TCM), known as the Fuzhengjiedu formula (FZJDF), has been shown to have anti-inflammatory benefits in both clinical and experimental studies. The precise underlying processes, nevertheless, are yet unclear.

PURPOSE

This study sought to enlighten the protective mechanism of FZJDF in ALI through the standpoint of the gut-lung crosstalk.

METHODS

The impact of FZJDF on lipopolysaccharide (LPS)-induced ALI murine model were investigated, and the lung injury score, serum interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) expression were measured to confirm its anti-inflammatory effects. Additionally, gut microbiota analysis and serum and fecal samples metabolomics were performed using metagenomic sequencing and high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry, respectively.

RESULTS

FZJDF significantly induced histopathological changes caused by LPS-induced ALI as well as downregulated the serum concentration of IL-1β and TNF-α. Furthermore, FZJDF had an effect in gut microbiota disturbances, and linear discriminant effect size analysis identified signal transduction, cell motility, and amino acid metabolism as the potential mechanisms of action in the FZJDF-treated group. Several metabolites in the LPS and FZJDF groups were distinguished by untargeted metabolomic analysis. Correlations were observed between the relative abundance of microbiota and metabolic products. Comprehensive network analysis revealed connections among lung damage, gut microbes, and metabolites. The expression of glycine, serine, glutamate, cysteine, and methionine in the lung and colon tissues was dysregulated in LPS-induced ALI, and FZJDF reversed these trends.

CONCLUSION

This study revealed that FZJDF considerably protected against LPS-induced ALI in mice by regulating amino acid metabolism via the gut-microbiota-lung axis and offered thorough and in-depth knowledge of the multi-system linkages of systemic illnesses.

Anti-Semaphorin-7A single chain antibody demonstrates beneficial effects on pulmonary inflammation during acute lung injury

Pulmonary inflammation is a primary characteristic of lung injury initiated by the accession of immune cells into the alveolar space. Neutrophil migration serves an important role in pulmonary inflammation mediated by the migration of neutrophils into hypoxic tissue sites. The elimination of pulmonary inflammation is directly associated with rehabilitation in patients with lung injury. Anti-inflammatory treatment is essential following lung injury and ultimately determines patient outcomes. Semaphorin-7A (SEMA-7A) is a member of the Semaphorin family that influences the migration of neutrophils into hypoxic tissue sites, thus promoting inflammation. However, understanding of the role of SEMA-7A serves during lung injury is limited and the immunological function of SEMA-7A during the migration of neutrophils into acute injury sites remains unknown. The present study investigated SEMA-7A expression and constructed a single chain antibody for SEMA-7A (Anti-SEMA-7A) to study its therapeutic efficacy against pulmonary inflammation in a mouse model of acute injury sites. The data indicated that the expression of SEMA-7A was upregulated due to induction by pro-inflammatory cytokines and demonstrated that Anti-SEMA-7A inhibited SEMA-7A expression in vitro and in vivo. The current study also indicated that the production of pro-inflammatory cytokines induced by SEMA-7A in endothelial and epithelial cells enhanced pulmonary inflammation. Anti-SEMA-7A suppressed the transendothelial migration of neutrophils mediated by SEMA-7A. Anti-SEMA-7A treatment neutralized SEMA-7A expression and reduced signs of pulmonary inflammation, leading to the elimination of pulmonary inflammation in rat with acute lung injury. The current study identified Anti-SEMA-7A as a potential agent to interfere with the inflammatory pathway during acute lung injury, which may be the basis for anti-inflammatory strategies to treat lung injuries in the future.

Astragalus membranaceus and Salvia miltiorrhiza Ameliorate Lipopolysaccharide-Induced Acute Lung Injury in Rats by Regulating the Toll-Like Receptor 4/Nuclear Factor-Kappa B Signaling Pathway

Astragalus membranaceus and Salvia miltiorrhiza (AM/SM) are well used in Traditional Chinese Medicines (TCM) for nourishing Qi and activating blood circulation method. From TCM theory, the pathogenesis of acute lung injury (ALI) was determined as Qi deficiency and blood stagnation. In this study, we are aiming to investigate the protective and therapeutic effects of AM/SM on a rat model of lipopolysaccharide- (LPS-) induced ALI in rats and to elucidate potential molecular mechanisms. ALI was induced by intratracheal instillation of LPS (5 mg/kg) in Sprague–Dawley rats. SM/AM was given orally before and after LPS administration. Results demonstrated that AM/SM attenuated lung histopathological changes induced by LPS, decreased wet/dry weight ratios and protein concentrations, and inhibited the production of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in BALF. Moreover, AM/SM significantly downregulated protein and mRNA expression of toll-like receptors 4 (TLR-4), interleukin-1 receptor-associated kinase-1 (IRAK-1), and nuclear factor-kappa B (NF-κB/p65). These findings suggest that AM/SM showed protective and therapeutic effects in LPS-induced ALI rat through modulating TLR-4 signaling pathways. Nourishing Qi and activating blood circulation may be a beneficial treatment for ALI.

The Role of IL-33 on LPS-Induced Acute Lung Injury in Mice

The objective of the study is to investigate the role and specific molecular mechanism of interleukin-33 (IL-33) acted on acute lung injury (ALI) induced by lipopolysaccharide (LPS). C57BL/6 mice intratracheally instilled LPS to induce ALI model. The mice were randomly divided into three groups: the sham operation group (Sham), ALI group (ALI), and pretreatment with IL-33 of ALI group (IL-33). By observing the survival rate, inflammatory cytokines in bronchoalveolar lavage fluid (BALF), myeloperoxidase (MPO) levels in lung tissue, lung histopathological examination, pulmonary capillary leakage, lung wet/dry (W/D) weight ratio, fibrosis levels in lung tissue, and associated pathways changes among the different groups, comparing to explore the role of IL-33 pretreatment on ALI mice and the possible molecular mechanisms. IL-33 pretreatment overall decreased the survival rate of ALI mice. IL-33 aggravated inflammation reaction showing as increasing the release of proinflammatory cytokines TNF-α and IL-6, increasing MPO levels in lung tissue, and aggravating lung pathology injury. In addition, IL-33 pretreatment further destroyed adherens junctions (AJs) by increasing the phosphorylation of VE-cadherin, resulting in the concomitantly pulmonary capillary barrier damage and pulmonary edema. During this process, mitogen-activated protein kinase (MAPK) pathways further activated. However, IL-33 pretreatment had no significant impact on collagen content of lung tissue. Our results indicated that IL-33 aggravated inflammatory reaction and increased microvascular permeability, but had little effect on pulmonary fibrosis, associated with the further activation of MAPK family proteins in the process. To sum up, IL-33 decreased survival rate and aggravated LPS-induced ALI.

Passive targeting of phosphatiosomes increases rolipram delivery to the lungs for treatment of acute lung injury: An animal study

A novel nanovesicle carrier, phosphatiosomes, was developed to enhance the targeting efficiency of phosphodiesterase 4 (PDE4) inhibitor to the lungs for treating acute lung injury (ALI) by intravenous administration. Phosphatiosomes were the basis of a niosomal system containing phosphatidylcholine (PC) and distearoylphosphatidylethanolamine polyethylene glycol (DSPE-PEG). Rolipram was used as the model drug loaded in the phosphatiosomes. Bioimaging, biodistribution, activated neutrophil inhibition, and ALI treatment were performed to evaluate the feasibility of phosphatiosomes as the lung-targeting carriers. An encapsulation percentage of >90% was achieved for rolipram-loaded nanovesicles. The vesicle size and zeta potential of the phosphatiosomes were 154 nm and -34 mV, respectively. Real-time imaging in rats showed a delayed and lower uptake of phosphatiosomes by the liver and spleen. Ex vivo bioimaging demonstrated a high accumulation of phosphatiosomes in the lungs. In vivo biodistribution exhibited increased lung accumulation and reduced brain penetration of rolipram in phosphatiosomes relative to the control solution. Phosphatiosomes improved the lungs/brain ratio of the drug by more than 7-fold. Interaction with pulmonary lipoprotein surfactants and the subsequent aggregation may be the mechanisms for facilitating lung targeting by phosphatiosomes. Rolipram could continue to inhibit active neutrophils after inclusion in the nanovesicles by suppressing O2(-) generation and elevating cAMP. Phosphatiosomes significantly alleviated ALI in mice as revealed by examining their pulmonary appearance, edema, myeloperoxidase (MPO) activity, and histopathology. This study highlights the potential of nanovesicles to deliver the drug for targeting the lungs and attenuating nervous system side effects.

Anti-Inflammatory Effects of Monoammonium Glycyrrhizinate on Lipopolysaccharide-Induced Acute Lung Injury in Mice through Regulating Nuclear Factor-Kappa B Signaling Pathway

The present study aimed to investigate the therapeutic effect of monoammonium glycyrrhizinate (MAG) on lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in mice and possible mechanism. Acute lung injury was induced in BALB/c mice by intratracheal instillation of LPS, and MAG was injected intraperitoneally 1 h prior to LPS administration. After ALI, the histopathology of lungs, lung wet/dry weight ratio, protein concentration, and inflammatory cells in the bronchoalveolar lavage fluid (BALF) were determined. The levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the BALF were measured by ELISA. The activation of NF-κB p65 and IκB-α of lung homogenate was detected by Western blot. Pretreatment with MAG attenuated lung histopathological damage induced by LPS and decreased lung wet/dry weight ratio and the concentrations of protein in BALF. At the same time, MAG reduced the number of inflammatory cells in lung and inhibited the production of TNF-α and IL-1β in BALF. Furthermore, we demonstrated that MAG suppressed activation of NF-κB signaling pathway induced by LPS in lung. The results suggested that the therapeutic mechanism of MAG on ALI may be attributed to the inhibition of NF-κB signaling pathway. Monoammonium glycyrrhizinate may be a potential therapeutic reagent for ALI.